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Gill AS, Sharma P, Nassar M, Marte E. Hypophosphatasia: A case report. World J Clin Cases 2025; 13:103642. [DOI: 10.12998/wjcc.v13.i21.103642] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/25/2024] [Revised: 01/28/2025] [Accepted: 03/27/2025] [Indexed: 04/27/2025] Open
Abstract
BACKGROUND Hypophosphatasia (HPP) is a rare metabolic disorder caused by low tissue-nonspecific alkaline phosphatase (ALP) activity, presenting symptoms from bone demineralization to tooth loss. It affects multiple systems and is diagnosed based on clinical symptoms, radiological findings, and lab tests. This case report emphasizes considering HPP in patients with unexplained bone pain and low ALP levels, especially with underlying osteopenia or osteoporosis. It highlights the importance of genetic testing and counseling for early diagnosis and treatment, aiming to raise clinician awareness.
CASE SUMMARY We present a case of a 65-year-old female patient who was referred to our endocrinology clinic for complaints of generalized bone pain and hypothyroidism. Initial evaluation revealed osteopenia, managed with calcium and vitamin D supplementation. Persistently low ALP levels and elevated vitamin B6 levels led to the diagnosis of HPP, confirmed by genetic testing identifying a pathogenic ALPL gene variant [c.119C>T (p.Ala40Val)]. Despite conservative treatment, her bone density declined, although remaining in the osteopenic range. The Fracture Risk Assessment score indicated a low risk of major osteoporotic and hip fractures, not warranting immediate treatment. Plans are underway to initiate enzyme replacement therapy with asfotase alfa.
CONCLUSION Recognizing HPP is crucial, as early diagnosis and treatment can significantly improve patient outcomes and prevent complications.
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Affiliation(s)
- Angad Singh Gill
- Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY 14221, United States
- Department of Research, American Society for Inclusion, Diversity, and Equity in Healthcare, Lewes, DE 19958, United States
| | - Pallavi Sharma
- Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY 14221, United States
- Department of Research, American Society for Inclusion, Diversity, and Equity in Healthcare, Lewes, DE 19958, United States
| | - Mahmoud Nassar
- Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY 14221, United States
- Department of Research, American Society for Inclusion, Diversity, and Equity in Healthcare, Lewes, DE 19958, United States
| | - Erlin Marte
- Department of Research, American Society for Inclusion, Diversity, and Equity in Healthcare, Lewes, DE 19958, United States
- Department of Endocrinology, Buffalo Veterans Affairs Medical Center, Buffalo, NY 14215, United States
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Prakash V, Elbabaa S, Banks R, de Carlos G, McAlister WH, Mumm S, Whyte MP. Markedly discordant hypophosphatasia in a young girl. Bone 2025:117541. [PMID: 40409424 DOI: 10.1016/j.bone.2025.117541] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2024] [Revised: 05/18/2025] [Accepted: 05/19/2025] [Indexed: 05/25/2025]
Abstract
Hypophosphatasia (HPP) is the inborn-error-of-metabolism from deactivating mutation(s) of ALPL, the gene that encodes the cell surface "tissue-nonspecific" isoenzyme of alkaline phosphatase (TNSALP). HPP's "biochemical signature" comprises low serum alkaline phosphatase activity together with elevated plasma levels of the TNSALP natural substrates phosphoethanolamine (PEA), pyridoxal 5'-phosphate (PLP), and inorganic pyrophosphate (PPi). Excess extracellular PPi (ePPi) inhibits mineralization and affected children prematurely shed deciduous teeth and often suffer weakness and rickets. Yet, HPP severity is greatest among all dento-osseous disorders and not fully explained by autosomal dominant versus autosomal recessive inheritance involving >470 ALPL mutations. Discordance of HPP phenotype sometimes manifests even among full siblings sharing an identical ALPL genotype. Herein, a girl's markedly discordant HPP featured at presentation life-threatening hypercalcemia, failure-to-thrive, and renal compromise. Subsequent pseudotumor cerebri syndrome caused blindness, and then craniosynostosis required cranial vault reconstruction. However, she was not deformed, had moderate hypophosphatasemia, normal plasma PLP level, and mild radiographic features of HPP rickets. Elevated plasma N-terminal parathyroid hormone-related protein (PTHrP) suggested malignancy, but corrected after kidney transplantation. HPP was diagnosed when whole exome sequencing revealed heterozygous ALPL c.1034C>T, p.A345V reported in mild pediatric HPP and transmitted by her mother who considered herself well. Genes conditioning ePPi formation and underlying other skeletal diseases were intact. Hypercalcemia, unresponsive to bone antiresorptive drugs, corrected promptly with asfotase alfa TNSALP supplementation therapy. Her markedly discordant findings highlight genotype/phenotype plasticity for pediatric HPP, and her clinical course importance for early diagnosis.
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Affiliation(s)
- Vikram Prakash
- Leon Pediatric Neuroscience Center of Excellence, Arnold Palmer Hospital for Children, Orlando, FL 32806, USA.
| | - Samer Elbabaa
- Leon Pediatric Neuroscience Center of Excellence, Arnold Palmer Hospital for Children, Orlando, FL 32806, USA.
| | - Richard Banks
- Endocrinology and Diabetes Center, Arnold Palmer Hospital for Children, Orlando, FL 32806, USA.
| | | | - William H McAlister
- Pediatric Radiology Section, Mallinckrodt Institute of Radiology at St. Louis Children's Hospital, Washington University School of Medicine, St. Louis, MO 63110, USA.
| | - Steven Mumm
- Center For Metabolic Bone Disease and Molecular Research, Shriners Hospitals for Children - St. Louis, St. Louis, MO 63110, USA; Division of Bone and Mineral Diseases, Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA.
| | - Michael P Whyte
- Center For Metabolic Bone Disease and Molecular Research, Shriners Hospitals for Children - St. Louis, St. Louis, MO 63110, USA; Division of Bone and Mineral Diseases, Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA.
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Salama M, Al Nofal A, Tebben P. Severe Hypercalcemia Associated With Perinatal Hypophosphatasia While Receiving Enzyme Replacement Therapy. JCEM CASE REPORTS 2025; 3:luaf066. [PMID: 40236614 PMCID: PMC11997545 DOI: 10.1210/jcemcr/luaf066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/10/2024] [Indexed: 04/17/2025]
Abstract
Hypophosphatasia (HPP) is characterized by defective bone mineralization due to reduced function of tissue-nonspecific alkaline phosphatase (TNSALP) caused by pathogenic ALPL gene variants. Hypercalcemia is more common in the perinatal and infantile forms and may be mitigated or prevented with enzyme replacement therapy asfotase alfa (AA). Here, we report a patient who developed severe hypercalcemia while receiving AA. Hypercalcemia was initially managed with intravenous fluids, dietary calcium restriction, and maximizing AA dose. Despite these measures, she required an additional hospital admission, at which time calcitonin 4 IU/kg every 12 hours was initiated. On this regimen, her calcium normalized without recurrence of severe hypercalcemia. Over the subsequent 8 months, restrictions of calcium intake were slowly lifted, and calcitonin was tapered and discontinued with maintenance of calcium within the normal range. This case underscores the significance of vigilant monitoring of calcium levels and dietary intake in infants diagnosed with HPP. While calcitonin is typically not considered as a sustained treatment for hypercalcemia, the present case illustrates the efficacy of adjunct calcitonin therapy, in conjunction with restricted calcium intake and maximum AA dosing, in managing severe hypercalcemia in an infant with perinatal HPP.
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Affiliation(s)
- Mostafa Salama
- Division of Pediatric Endocrinology and Metabolism, Mayo Clinic, Rochester, MN 55905, USA
| | - Alaa Al Nofal
- Division of Pediatric Endocrinology and Metabolism, Mayo Clinic, Rochester, MN 55905, USA
| | - Peter Tebben
- Division of Pediatric Endocrinology and Metabolism, Mayo Clinic, Rochester, MN 55905, USA
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Wang S, Sun L, Hu J, Zhang Q, Wang O, Jiang Y, Xia W, Xing X, Li M. Effects of asfotase alfa on fracture healing of adult patient with hypophosphatasia and literature review. Orphanet J Rare Dis 2025; 20:162. [PMID: 40189581 PMCID: PMC11974181 DOI: 10.1186/s13023-025-03663-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2024] [Accepted: 03/15/2025] [Indexed: 04/09/2025] Open
Abstract
OBJECTIVE Hypophosphatasia (HPP) is a rare inherited disorder caused by ALPL gene mutations, with fracture nonunion being a serious complication. This study investigated the effects of teriparatide and asfotase alfa (AA) on femoral fracture healing of an adult patient with HPP, accompanied with a literature review. METHODS A 37-year-old woman wheelchair-bound was diagnosed with HPP due to an extremely low serum alkaline phosphatase (ALP) level (4-10 U/L), who suffered from bilateral femur pain and non-union of femoral shaft fractures on both sides. Compound heterozygous missense mutations (c.382G > A and c.461C > T) were identified in exon5 of ALPL gene. The patient received teriparatide sequential AA therapy. Serum levels of ALP, β-isomerized carboxy-telopeptide of type I collagen (β-CTX) and procollagen type 1 amino-terminal peptide (P1NP), bone mineral density (BMD) and skeletal X-ray were measured during the treatment. Literature was searched by keywords of "Hypophosphatasia", "HPP", "ALPL", "TNSALP", "ALP" combined with "Asfotase alfa", "AA", "enzyme replacement therapy", and "ERT". RESULTS After unsuccessful 6-month teriparatide treatment for femoral fracture, AA treatment was initiated, at a dose of 2 mg/kg, 3 times a week. After the first month of AA treatment, serum ALP level increased from 4 to 9206 U/L, and serum calcium and phosphate levels decreased, with increase in PTH, β-CTX, and P1NP levels. After 4 months of AA treatment, her bone pain significantly alleviated, accompanied by significant shortening of the fracture line. After 10 months of AA therapy, the fracture demonstrated complete healing and the patient could walk independently. BMD at lumbar spine and hips was significantly increased. Among 295 adult patients with HPP reported in the literature, 213 (72.2%) exhibited skeletal-related symptoms and 91 (30.8%) presented with bone fractures. In addition to skeletal manifestations, the patients presented with early tooth loss, muscle weakness and ectopic calcification. AA treatment, spanning 9 weeks to 3 years, has been shown to increase ALP levels, promote fracture healing, improve mobility, and alleviate bone pain. CONCLUSION Adult HPP patients mainly present with recurrent or poorly healing fractures, bone pain, and early loss of teeth. AA replacement therapy can effectively promote fracture healing, relieve bone pain, and enhance mobility.
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Affiliation(s)
- Songqi Wang
- Department of Endocrinology, National Health Commission Key Laboratory of Endocrinology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100730, China
| | - Lei Sun
- Department of Endocrinology, National Health Commission Key Laboratory of Endocrinology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100730, China
| | - Jing Hu
- Department of Endocrinology, National Health Commission Key Laboratory of Endocrinology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100730, China
| | - Qian Zhang
- Department of Endocrinology, National Health Commission Key Laboratory of Endocrinology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100730, China
| | - Ou Wang
- Department of Endocrinology, National Health Commission Key Laboratory of Endocrinology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100730, China
| | - Yan Jiang
- Department of Endocrinology, National Health Commission Key Laboratory of Endocrinology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100730, China
| | - Weibo Xia
- Department of Endocrinology, National Health Commission Key Laboratory of Endocrinology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100730, China
| | - Xiaoping Xing
- Department of Endocrinology, National Health Commission Key Laboratory of Endocrinology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100730, China
| | - Mei Li
- Department of Endocrinology, National Health Commission Key Laboratory of Endocrinology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100730, China.
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Wen W, Zhe W, Qianxiu C, Haixia S, Zongchao F, Jing H, Hao L. Disproportionality analysis of adverse events associated with asfotase alfa: a post-marketing study using the FDA Adverse Event Reporting System. Expert Opin Drug Saf 2025; 24:435-443. [PMID: 39604191 DOI: 10.1080/14740338.2024.2433566] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2024] [Accepted: 11/18/2024] [Indexed: 11/29/2024]
Abstract
BACKGROUND Asfotase alfa (AA) is an FDA-approved enzyme replacement therapy for hypophosphatasia (HPP). Limited real-world data on its adverse events (AEs) exist. This study evaluates AA-related AEs using the U.S. FDA's Adverse Event Reporting System (FAERS) database. METHODS Reports for AA were extracted from FAERS and analyzed per FDA guidelines. AEs were categorized using MedDRA version 26.1. Disproportionality analysis was conducted using the reporting odds ratio (ROR), proportional reporting ratio (PRR), Bayesian confidence propagation neural network (BCPNN), and empirical Bayes geometric mean (EBGM) algorithms. Time-to-onset (TTO) was calculated, with a Weibull shape parameter test to assess risk over time. RESULTS Out of 13,702,373 reports, 5,040 AA-related AEs were identified, with 198 significant preferred terms (PTs). Common AEs included injection site reactions and pain, with additional PTs for ear/labyrinth disorders and infections. The median onset for 234 AEs with reported times was 170 days (IQR 18-390 days). No significant differences in AEs were found across gender or age groups. CONCLUSION Most AEs align with known data, but newly identified ear/labyrinth disorders and infections require further investigation to enhance AA's safety profile.
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Affiliation(s)
- Wang Wen
- Department of Pediatrics, Jinan Massage Hospital, Jinan, China
- Department of Rehabilitation, Jinan Massage Hospital, Jinan, China
| | - Wang Zhe
- College of Acupuncture and Tuina, Shandong University of Traditional Chinese Medicine, Jinan, China
| | - Chen Qianxiu
- College of Acupuncture and Tuina, Shandong University of Traditional Chinese Medicine, Jinan, China
| | - Sun Haixia
- Department of Pediatrics, Jinan Massage Hospital, Jinan, China
- Department of Rehabilitation, Jinan Massage Hospital, Jinan, China
| | - Fu Zongchao
- Department of Pediatrics, Jinan Massage Hospital, Jinan, China
- Department of Rehabilitation, Jinan Massage Hospital, Jinan, China
| | - Han Jing
- Department of Acupuncture, Affiliated Hospital of Shandong University of Traditional Chinese Medicine, Jinan, China
| | - Lv Hao
- Department of Pediatric Orthopedics, Affiliated Hospital of Shandong University of Traditional Chinese Medicine, Jinan, China
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Minisola S, Cipriani C, Colangelo L, Labbadia G, Pepe J, Magnusson P. Diagnostic Approach to Abnormal Alkaline Phosphatase Value. Mayo Clin Proc 2025; 100:712-728. [PMID: 40019430 DOI: 10.1016/j.mayocp.2024.11.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/09/2024] [Revised: 11/04/2024] [Accepted: 11/20/2024] [Indexed: 03/01/2025]
Abstract
Alkaline phosphatase (ALP) is abundantly represented in nature, being fundamental for a number of processes. In addition to its fundamental function in skeletal mineralization, its roles in the pathogenesis of other diseases are being explored. The measurement of total ALP activity in serum or in plasma is a useful biomarker in clinical practice. Indeed, routine measurement of serum total ALP is a long-standing established part of initial biochemical evaluation of patients both in the hospital setting and on an ambulatory basis. Raised or reduced values of this enzyme activity are indicative of a number of diseases, most commonly affecting the skeleton and the biliary tract. Electrophoretic assays are preferable for visualizing and investigating the cause of increased serum total ALP activities, and bone ALP immunoassays are preferable for investigating and monitoring individuals with bone and mineral metabolic abnormalities. Here, we give a holistic vision of this fundamental enzyme, suggesting a clinical approach to the identification of diseases causing abnormal values. Finally, a therapeutic role has emerged as substitutive therapy in patients with hypophosphatasia, even though ongoing and future studies are exploring its role in other therapeutic areas. This narrative review was based on articles found by searching PubMed from its inception until July 2024 for the terms alkaline phosphatases, isozymes, isoforms, bone alkaline phosphatase, liver alkaline phosphatase, intestinal alkaline phosphatase, placental alkaline phosphatase, liver function tests, γ-glutamyltransferase, skeletal diseases, and liver diseases. We limited our research to papers published in the English language, with emphasis placed on those describing differential diagnosis whenever available.
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Affiliation(s)
- Salvatore Minisola
- Department of Clinical, Internal, Anesthesiologic, and Cardiovascular Sciences, "Sapienza" University of Rome, Rome, Italy.
| | - Cristiana Cipriani
- Department of Clinical, Internal, Anesthesiologic, and Cardiovascular Sciences, "Sapienza" University of Rome, Rome, Italy
| | - Luciano Colangelo
- Department of Clinical, Internal, Anesthesiologic, and Cardiovascular Sciences, "Sapienza" University of Rome, Rome, Italy
| | - Giancarlo Labbadia
- Department of Clinical, Internal, Anesthesiologic, and Cardiovascular Sciences, "Sapienza" University of Rome, Rome, Italy
| | - Jessica Pepe
- Department of Clinical, Internal, Anesthesiologic, and Cardiovascular Sciences, "Sapienza" University of Rome, Rome, Italy
| | - Per Magnusson
- Department of Clinical Chemistry and Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
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Dahir KM, Dunbar NS. Medical Management of Hypophosphatasia: Review of Data on Asfotase Alfa. Curr Osteoporos Rep 2025; 23:14. [PMID: 40100438 PMCID: PMC11920343 DOI: 10.1007/s11914-025-00906-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 02/17/2025] [Indexed: 03/20/2025]
Abstract
PURPOSE Hypophosphatasia (HPP) is a rare, dento-osseous disorder caused by impaired activity of tissue non-specific alkaline phosphatase (TNSALP), a key enzyme in tissue mineralization. This review provides a clinical perspective on the current medical treatment of both children and adults with HPP. RECENT FINDINGS Dental problems, rickets in children, and osteomalacia in adults are common in HPP. However, disease manifestations in individual patients are exceptionally variable. Recent studies broadened our understanding of HPP symptoms. For example, data showed behavioral health challenges in HPP children, and a large, real-world data set from the Global HPP Registry demonstrated that HPP adults regardless of the time of disease onset exhibit significant disease burden and are broadly affected by non-skeletal impairments, such as pain and chronic fatigue. Treatment for HPP relies on the enzyme replacement asfotase alfa. Small, mostly pediatric trials initially established dosing, safety and efficacy of asfotase alfa, and latest data corroborated the long-term safety and efficacy in both children and pediatric-onset adults. Data from several recent observational studies, including the Global HPP Registry, underscored that asfotase alfa improves physical functions, non-skeletal symptoms such as pain, and quality-of-life (QoL) in adults irrespective of age-of-onset. Clinical use of asfotase alfa is based on prescribing information and evidence-based consensus guidelines. However, recommendations for initiation of therapy are just emerging. Alternatives to asfotase alfa remain limited, but a derivative, efzimfotase alfa, currently undergoes clinical testing. Studies in larger HPP patient populations suggest efficacy of enzyme replacement therapy independent of patient age and time of disease onset.
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Affiliation(s)
- Kathryn McCrystal Dahir
- Program for Metabolic Bone Disorders at Vanderbilt, Endocrinology and Diabetes, Division of Endocrinology, Vanderbilt University Medical Center, 8210 Medical Center East, 1215 21St Avenue South, Nashville, TN, 37232-8148, USA.
| | - Nancy S Dunbar
- Pediatric Metabolic Bone Program, Division of Pediatric Endocrinology, Connecticut Children's Medical Center, Farmington, CT, 06117, USA
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Okawa R, Kadota T, Kurosaka H, Nakayama H, Ochiai M, Ogaya Y, Kubota T, Yamashiro T, Nakano K. Japanese nationwide dental survey of hypophosphatasia reveals novel oral manifestations. Sci Rep 2025; 15:6743. [PMID: 40000791 PMCID: PMC11861587 DOI: 10.1038/s41598-025-91043-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2024] [Accepted: 02/18/2025] [Indexed: 02/27/2025] Open
Abstract
Hypophosphatasia (HPP) is a common inherited skeletal disease. Early exfoliation of primary teeth is known as a dental manifestation of HPP, and sometimes this symptom leads to a diagnosis of HPP. This study aimed to investigate the dental manifestations of HPP in the Japanese population, focusing on dentition and occlusion. A total of 609 dental clinics among general hospitals with dentistry departments were invited to participate. Clinics were sent questionnaires about the number of HPP cases encountered from 2018 to 2022. When clinics indicated that they had treated HPP cases, we proceeded with a second questionnaire about the clinical dental findings of these cases. A total of 103 clinical records of HPP from 30 clinics were collected. Forty percent of non-odonto type cases showed enamel hypomineralization, which was significantly higher than the incidence found in odonto type cases (8.5%) (P < 0.001). Non-odonto type cases also exhibited malocclusion (40.0%), poor oral habits (29.1%), and dysphagia (23.6%). The number of dental visits made by HPP patients is increasing because of the development of new treatments and increased disease awareness. Dental symptoms of HPP vary in severity, with particularly severe forms of HPP associated with enamel hypomineralization, malocclusion, poor oral habits, and dysphagia. Patients with HPP require not only medical collaboration but also multidisciplinary dental care according to the severity of the disease.
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Affiliation(s)
- Rena Okawa
- Department of Pediatric Dentistry, Graduate School of Dentistry, The University of Osaka, 1-8 Yamadaoka, Suita, Osaka, 565-0871, Japan.
| | - Tamami Kadota
- Department of Pediatric Dentistry, Graduate School of Dentistry, The University of Osaka, 1-8 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Hiroshi Kurosaka
- Department of Orthodontics and Dentofacial Orthopedics, Graduate School of Dentistry, The University of Osaka, 1-8 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Hirofumi Nakayama
- Department of Pediatrics, Graduate School of Medicine, The University of Osaka, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Marin Ochiai
- Department of Pediatric Dentistry, Graduate School of Dentistry, The University of Osaka, 1-8 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Yuko Ogaya
- Department of Pediatric Dentistry, Graduate School of Dentistry, The University of Osaka, 1-8 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Takuo Kubota
- Department of Pediatrics, Graduate School of Medicine, The University of Osaka, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Takashi Yamashiro
- Department of Orthodontics and Dentofacial Orthopedics, Graduate School of Dentistry, The University of Osaka, 1-8 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Kazuhiko Nakano
- Department of Pediatric Dentistry, Graduate School of Dentistry, The University of Osaka, 1-8 Yamadaoka, Suita, Osaka, 565-0871, Japan
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Castells Vilella L, Sánchez-Pintos P, Muñiz Llama JF, Gámez Martínez M, Couce ML, Antón J. Age- and Sex-Dynamic Fluctuations and Reference Intervals for Alkaline Phosphatase Among the Spanish Population. Arch Pathol Lab Med 2025; 149:e19-e25. [PMID: 38797525 DOI: 10.5858/arpa.2023-0335-oa] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/21/2024] [Indexed: 05/29/2024]
Abstract
CONTEXT.— Interpretation of alkaline phosphatase (ALP) activity is essential for the diagnosis of certain diseases. ALP changes during life and may vary between different populations. OBJECTIVE.— To establish reference intervals (RIs) and percentile charts for ALP activity in the Spanish population through a multicentric observational study and to compare the RIs to those defined in other countries. DESIGN.— A total of 662 350 ALP measurements from individuals ages 0 to 99 years from 9 Spanish tertiary care centers collected between 2020 and 2022 were analyzed. This study is the largest published on this topic in the literature to date. RESULTS.— Continuous percentile charts for ALP according to sex and age were established which can be used as RIs. Higher levels are reached during the first weeks of life. In puberty, a differential evolution is observed in both sexes, reaching a peak at 10 to 13 years of age in boys and remaining stable in girls at this age. Significant differences were also observed in adults, higher in men between ages 20 and 49 years and between ages 50 and 79 years in women, as reported in some countries. CONCLUSIONS.— ALP activity follows an age- and sex-dependent fluctuation with geographic differences. It is important to have appropriate reference values for each population in order to allow for a correct diagnostic interpretation and early diagnosis of diseases related to ALP abnormalities.
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Affiliation(s)
- Laura Castells Vilella
- From the Department of Pediatrics, Hospital Universitari General de Catalunya, Grupo Quirónsalud, Sant Cugat del Vallès, Barcelona, Spain (Castells Vilella, Muñiz Llama)
| | - Paula Sánchez-Pintos
- the Diagnosis and Treatment Unit of Congenital Metabolic Diseases, Department of Pediatrics, University Clinical Hospital of Santiago de Compostela, Santiago de Compostela, Spain (Sánchez-Pintos, Couce)
- IDIS-Health Research Institute of Santiago de Compostela, Santiago de Compostela, Spain (Sánchez-Pintos, Couce)
- CIBERER, Instituto Salud Carlos III, Madrid, Spain (Sánchez-Pintos, Couce)
- MetabERN, Udine, Italy (Sánchez-Pintos, Couce)
| | - José Félix Muñiz Llama
- From the Department of Pediatrics, Hospital Universitari General de Catalunya, Grupo Quirónsalud, Sant Cugat del Vallès, Barcelona, Spain (Castells Vilella, Muñiz Llama)
| | - Matías Gámez Martínez
- Quantitative Methods and Socioeconomic Development, Institute for Regional Development, University of Castilla-La Mancha (Gámez Martínez)
| | - María Luz Couce
- the Diagnosis and Treatment Unit of Congenital Metabolic Diseases, Department of Pediatrics, University Clinical Hospital of Santiago de Compostela, Santiago de Compostela, Spain (Sánchez-Pintos, Couce)
- IDIS-Health Research Institute of Santiago de Compostela, Santiago de Compostela, Spain (Sánchez-Pintos, Couce)
- CIBERER, Instituto Salud Carlos III, Madrid, Spain (Sánchez-Pintos, Couce)
- MetabERN, Udine, Italy (Sánchez-Pintos, Couce)
| | - Jordi Antón
- Pediatric Rheumatology Division, Hospital Sant Joan de Déu, Barcelona, Spain (Antón)
- Immune Deficiency Dysfunction Diseases in Pediatrics (GEMDIP), Institut de Recerca Sant Joan de Déu, Barcelona, Spain (Antón)
- the Department of Surgery and Surgical Specializations at the Facultat de Medicina i Ciències de la Salut, University of Barcelona, Barcelona, Spain (Antón)
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Pijeira Perez Y, Hughes DA. Evidence Following Conditional NICE Technology Appraisal Recommendations: A Critical Analysis of Methods, Quality and Risk of Bias. PHARMACOECONOMICS 2024; 42:1373-1394. [PMID: 39249730 PMCID: PMC11564307 DOI: 10.1007/s40273-024-01418-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 07/14/2024] [Indexed: 09/10/2024]
Abstract
BACKGROUND The National Institute for Health and Care Excellence (NICE) may approve health technologies on condition of more evidence generated only in research (OiR) or only with research (OwR). NICE specifies the information needed to comply with its request, although it may not necessarily guarantee good quality and timely evidence for re-appraisal, before reaching a final decision. AIM This study aimed to critically appraise the methods, quality and risk of bias of evidence generated in response to NICE OiR and OwR technology appraisal (TA) and highly specialised technologies (HSTs) recommendations. METHODS NICE TAs (between March 2000 and September 2020) and HST evaluations (to October 2023) of medicines were reviewed. Conditional recommendations were analysed to identify the evidence requested by NICE for re-appraisal. The new evidence was analysed for compliance with NICE's request and assessed using the Cochrane Collaboration's tools for risk of bias in randomised trials and the ROBINS-I tool for non-randomised evidence. RESULTS NICE made 54 conditional recommendations from TAs (13 OiR and 41 OwR) and five conditional recommendations for HSTs (all OwR). Of these, 16 TAs presented additional evidence for re-appraisal (9 OiR [69%] and 7 OwR [17%]) and three HSTs (3 OwR [60%]). Two of the nine re-appraised TAs with OiR recommendation and four of the seven OwR complied fully with NICE's request for further evidence, while all three from the HSTs complied. The majority of re-appraised TAs and HSTs included evidence that was deemed to be at serious, high, moderate or unclear risk of bias. Among the 26 randomised controlled trials from TAs assessed, eight were categorised as having low risk of bias in all domains and ten had at least one domain as a high risk of bias. Reporting was unclear for the remainder. Twenty-two non-randomised studies, primarily single-arm studies, were susceptible to biases mostly due to the selection of participants and to confounding. Two HSTs provided evidence from randomised controlled trials which were classified as unclear or high risk of bias. All non-randomised evidence from HSTs were categorised as moderate or serious risk of bias. CONCLUSIONS There is widespread non-compliance with agreed data requests and important variation in the quality of evidence submitted in response to NICE conditional approval recommendations. Quality standards ought to be stipulated in respect to evidence contributing to re-appraisals following NICE conditional approval recommendations.
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Affiliation(s)
- Yankier Pijeira Perez
- Centre for Health Economics and Medicines Evaluation, Bangor University, Ardudwy, Normal Site, Holyhead Road, Bangor, Gwynedd, Wales, LL57 2PZ, UK
| | - Dyfrig A Hughes
- Centre for Health Economics and Medicines Evaluation, Bangor University, Ardudwy, Normal Site, Holyhead Road, Bangor, Gwynedd, Wales, LL57 2PZ, UK.
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11
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Schindeler A, Ludwig K, Munns CF. Enzyme replacement therapy for hypophosphatasia-The current paradigm. Clin Endocrinol (Oxf) 2024; 101:593-601. [PMID: 39004952 DOI: 10.1111/cen.15063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Revised: 02/21/2024] [Accepted: 04/15/2024] [Indexed: 07/16/2024]
Abstract
Hypophosphatasia (HPP) is a rare, inherited, and systemic disorder characterized by impaired skeletal mineralization and low tissue nonspecific serum alkaline phosphatase (TNSALP) activity. It is caused by either autosomal recessive or dominant-negative mutations in the gene that encodes TNSALP. The phenotype of HPP is very broad including abnormal bone mineralization, disturbances of calcium and phosphate metabolism, pain, recurrent fracture, short stature, respiratory impairment, developmental delay, tooth loss, seizures, and premature death. Other than supportive care, there has been no disease-specific treatment available for those with HPP. Asfotase alfa is a fully humanized, recombinant enzyme replacement therapy for the management of HPP. It is available in several countries for the treatment of the more severe forms of HPP, namely perinatal and infantile HPP. This review will summarize the preclinical data on asfotase alfa and highlight the data from clinical trials and case reports. These data show the transformative nature of asfotase alfa when administered as part of an interdisciplinary treatment model.
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Affiliation(s)
- Aaron Schindeler
- Bioengineering and Molecular Medicine Laboratory, The Children's Hospital at Westmead and Westmead Institute for Medical Research, Westmead, New South Wales, Australia
- Children's Hospital at Westmead Clinical School, University of Sydney, Camperdown, New South Wales, Australia
| | - Karissa Ludwig
- Child Health Research Centre and Faculty of Medicine, The University of Queensland, Brisbane, Queensland, Australia
- Department of Endocrinology, Queensland Children's Hospital, Brisbane, Queensland, Australia
| | - Craig F Munns
- Child Health Research Centre and Faculty of Medicine, The University of Queensland, Brisbane, Queensland, Australia
- Department of Endocrinology, Queensland Children's Hospital, Brisbane, Queensland, Australia
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12
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Shirinezhad A, Esmaeili S, Azarboo A, Tavakoli Y, Hoveidaei AH, Zareshahi N, Ghaseminejad-Raeini A. Efficacy and safety of asfotase alfa in patients with hypophosphatasia: A systematic review. Bone 2024; 188:117219. [PMID: 39089608 DOI: 10.1016/j.bone.2024.117219] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/15/2024] [Revised: 07/18/2024] [Accepted: 07/28/2024] [Indexed: 08/04/2024]
Abstract
BACKGROUND Hypophosphatasia (HPP) is a rare genetic disorder characterized by defective bone mineralization, leading to skeletal abnormalities and systemic complications. Asfotase alfa, a recombinant human tissue-nonspecific alkaline phosphatase (TNSALP) enzyme replacement therapy, has emerged as a promising treatment for HPP. However, a comprehensive evaluation of its efficacy and safety is warranted to guide clinical practice effectively. METHODS The study followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and was registered in Prospective Register of Systematic Reviews (PROSPERO). A search strategy across databases found studies on asfotase alfa for HPP. Two researchers independently extracted and assessed data. This systematic review examined how the drug impacted clinical outcomes such as survival rates, musculoskeletal symptoms, respiratory function, growth measurements, dental health, quality of life, and laboratory results. RESULTS This systematic review included 15 articles with a total of 455 HPP patients. Asfotase alfa was predominantly administered at a dose of 6 mg per kg per week among the reviewed studies. Notable findings included enhanced survival rates, relief from musculoskeletal pain, improvements in respiratory outcomes, growth parameters, dental health, and quality of life. Changes in laboratory variables indicated positive responses to treatment, including changes such as increase in alkaline phosphatase (ALP), decline in pyridoxal 5'-phosphate (PLP) and inorganic pyrophosphate (PPi) levels. CONCLUSION Asfotase alfa demonstrates efficacy in improving clinical outcomes and safety in patients with HPP. Its therapeutic benefits extend across various domains. However, Larger, age-stratified comparative studies are needed to further investigate the drug's effects in HPP patients.
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Affiliation(s)
| | - Sina Esmaeili
- Sina University Hospital, Tehran University of Medical Sciences, Tehran, Iran
| | - Alireza Azarboo
- School of Medicine, Tehran University of Medical Sciences, Tehran, Iran.
| | - Yasaman Tavakoli
- Student Research Committee, Department of Medicine, Mazandaran University of Medical Sciences, Mazandaran, Iran
| | - Amir Human Hoveidaei
- International Center for Limb Lengthening, Rubin Institute for Advanced Orthopedics, Sinai Hospital of Baltimore, Baltimore, Maryland, USA
| | - Negar Zareshahi
- School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
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13
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Dahir KM, Shannon A, Dunn D, Voegtli W, Dong Q, Hasan J, Pradhan R, Pelto R, Pan WJ. Safety, pharmacokinetics, and pharmacodynamics of efzimfotase alfa, a second-generation enzyme replacement therapy: phase 1, dose-escalation study in adults with hypophosphatasia. J Bone Miner Res 2024; 39:1412-1423. [PMID: 39135540 PMCID: PMC11425692 DOI: 10.1093/jbmr/zjae128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2024] [Revised: 07/26/2024] [Accepted: 08/04/2024] [Indexed: 09/27/2024]
Abstract
Hypophosphatasia (HPP) is a rare, inherited metabolic disease caused by deficient activity of tissue-nonspecific alkaline phosphatase (TNSALP). Efzimfotase alfa (ALXN1850) is a second-generation TNSALP enzyme replacement therapy in development for HPP. This first-in-human open-label, dose-escalating phase 1 trial evaluated efzimfotase alfa safety, tolerability, pharmacokinetics, pharmacodynamics, and immunogenicity. Fifteen adults (5/cohort) with HPP received efzimfotase alfa in doses of 15 mg (cohort 1), 45 mg (cohort 2), or 90 mg (cohort 3) as one intravenous (i.v.) dose followed by 3 weekly subcutaneous (s.c.) doses. The primary objective was to assess safety and tolerability. Secondary objectives included pharmacokinetics, pharmacodynamics of ALP substrates known to be biomarkers of disease (inorganic pyrophosphate [PPi] and pyridoxal 5'-phosphate [PLP]) and immunogenicity. Treatment-emergent adverse events (TEAEs) occurred in 12 (80%) participants. Eight (53%) participants had injection site reactions (ISRs), observed after 10 of 41 (24%) s.c. injections. Most ISR TEAEs were mild and resolved within 1-2 d. Peak and total exposures of efzimfotase alfa increased in a greater-than-dose proportional manner over the range of 15-90 mg after i.v. and s.c. dosing. The arithmetic mean elimination half-life was approximately 6 d; absolute bioavailability was 28.6%-36.8% over the s.c. dose range of 15-90 mg. Dose-dependent reductions in plasma concentrations of PPi and PLP relative to baseline reached nadir in the first week after i.v. dosing and were sustained for 3-4 wk after the last s.c. dose. Four (27%) participants tested positive for antidrug antibodies (ADAs), 3 of whom were ADA positive before the first dose of efzimfotase alfa. ADAs had no apparent effect on efzimfotase alfa pharmacokinetics/pharmacodynamics. No participants had neutralizing antibodies. Efzimfotase alfa demonstrated acceptable safety, tolerability, and pharmacokinetic profiles and was associated with sustained reductions in biomarkers of disease in adults with HPP, supporting further evaluation in adult and pediatric patients. Registration: ClinicalTrials.gov NCT04980248 (https://clinicaltrials.gov/study/NCT04980248).
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Affiliation(s)
- Kathryn M Dahir
- Program for Metabolic Bone Disorders, Vanderbilt University Medical Center, Nashville, TN 37232-8148, United States
| | - Amy Shannon
- Development, Regulatory and Safety, Alexion, AstraZeneca Rare Disease, Boston, MA 02210, United States
| | - Derek Dunn
- Development, Regulatory and Safety, Alexion, AstraZeneca Rare Disease, Boston, MA 02210, United States
| | - Walter Voegtli
- Development, Regulatory and Safety, Alexion, AstraZeneca Rare Disease, Boston, MA 02210, United States
| | - Qunming Dong
- Development, Regulatory and Safety, Alexion, AstraZeneca Rare Disease, Boston, MA 02210, United States
| | - Jawad Hasan
- Development, Regulatory and Safety, Alexion, AstraZeneca Rare Disease, Boston, MA 02210, United States
| | - Rajendra Pradhan
- Development, Regulatory and Safety, Alexion, AstraZeneca Rare Disease, Boston, MA 02210, United States
| | - Ryan Pelto
- Bioanalytical and Biomarker Development, Alexion, AstraZeneca Rare Disease, New Haven, CT 06510, United States
| | - Wei-Jian Pan
- Development, Regulatory and Safety, Alexion, AstraZeneca Rare Disease, Boston, MA 02210, United States
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14
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Dahir KM, Ing SW, Deal C, Messali A, Bates T, Rush ET. Improvement in quality of life after asfotase alfa treatment in adults with pediatric-onset hypophosphatasia: data from 5 patient-reported outcome measures. JBMR Plus 2024; 8:ziae062. [PMID: 39006866 PMCID: PMC11245646 DOI: 10.1093/jbmrpl/ziae062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Revised: 04/09/2024] [Accepted: 05/02/2024] [Indexed: 07/16/2024] Open
Abstract
Hypophosphatasia (HPP) is a rare, inherited metabolic disorder caused by deficient tissue-nonspecific alkaline phosphatase activity. This study assessed the impact of treatment with asfotase alfa on patient-reported outcomes (PROs) in adults with pediatric-onset HPP. A longitudinal, telephone-based survey was administered to eligible individuals enrolled in a patient support program. Interviews were conducted at study entry (prior to asfotase alfa initiation) and after 3, 6, and 12 mo. PROs-Patient Health Questionnaire-9 [PHQ-9], Work Productivity and Activity Impairment Questionnaire: Specific Health Problem [WPAI:SHP], Patient-Reported Outcomes Measurement Information System 29 [PROMIS-29], and Routine Assessment of Patient Index Data 3 [RAPID3]-were assessed at each time point. Appropriate statistical tests were performed to assess score changes. Among 50 enrolled patients (mean age: 46 yr [SD: 15.4]; 80% female; 94% White), 49 were evaluable at 3 mo, 44 at 6 mo, and 29 at 12 mo. By month 3, statistically significant improvements from baseline were detected in PHQ-9 scores (10.6 vs 5.8 [P < .0001]), PROMIS-29 domain scores (overall physical function: 38.0 vs 43.0 [P = .001]; anxiety: 57.5 vs 51.5 [P = .0011]; fatigue: 63.3 vs 55.3 [P < .0001]; sleep disturbances: 58.8 vs 54.3 [P = .0099]; ability to participate in social roles and activities: 42.6 vs 47.7 [P = .0012]; and pain interference: 63.8 vs 58.4 [P = .001]), and RAPID3 domain scores (functional status: 2.7 vs 1.1 [P < .0001]; pain tolerance: 6.0 vs 3.2 [P < .0001]; and global health estimate: 5.1 vs 2.7 [P < .0001]). Improvements persisted at month 12. Patients also showed improvements in WPAI:SHP domain scores at month 6 (presenteeism: 39.6% vs 14.1% [P < .0001] and work productivity loss: 41.9% vs 14.1% [P < .0001]). Treatment with asfotase alfa was associated with improved quality of life across several domains.
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Affiliation(s)
- Kathryn M Dahir
- Endocrinology and Diabetes, Vanderbilt University Medical Center, Nashville, TN 37232, United States
| | - Steven W Ing
- Division of Endocrinology, Diabetes, and Metabolism, Wexner Medical Center, Ohio State University, Columbus, OH 43210, United States
| | - Chad Deal
- Department of Rheumatology, Center for Osteoporosis and Metabolic Bone Disease, Cleveland Clinic, Cleveland, OH 44195, United States
| | - Andrew Messali
- Health Economics and Outcomes Research (AM) and Medical Affairs (CD), Alexion, AstraZeneca Rare Disease, Boston, MA 02210, United States
| | - Toby Bates
- Health Economics and Outcomes Research (AM) and Medical Affairs (CD), Alexion, AstraZeneca Rare Disease, Boston, MA 02210, United States
| | - Eric T Rush
- Division of Clinical Genetics, Children's Mercy Kansas City, Kansas City, MO 64108, United States
- Department of Pediatrics, University of Missouri - Kansas City School of Medicine, Kansas City, MO 64108, United States
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15
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Araya CE, Mercer ES, Asplin JR, Best SL. First reported magnesium pyrophosphate kidney stone prompts diagnosis of hypophosphatasia. Urol Case Rep 2024; 55:102791. [PMID: 39091420 PMCID: PMC11292424 DOI: 10.1016/j.eucr.2024.102791] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2024] [Revised: 06/26/2024] [Accepted: 07/02/2024] [Indexed: 08/04/2024] Open
Abstract
Hypophosphatasia (HPP) is a rare genetic condition associated with poor bone mineralization, low serum alkaline phosphatase, high urinary pyrophosphate excretion, and nephrocalcinosis. Nephrocalcinosis is thought to develop due to the increased filtered loads associated with hypercalcemia and hyperphosphatemia, but the composition of these calcifications is incompletely understood. We report the first ever magnesium pyrophosphate (MgPPi) urinary stone, which prompted the new diagnosis of HPP in a 12-year-old boy. Stone analysis labs should include infrared spectra of PPi salts in their reference libraries to facilitate identification of these rare but clinically important stones.
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Affiliation(s)
- Carlos E. Araya
- Nemours Children's Health, 6535 Nemours Parkway, Orlando, FL, 32827, USA
| | - Erica S. Mercer
- Nemours Children's Health, 807 Children's Way, Jacksonville, FL, 32207, USA
| | - John R. Asplin
- Labcorp Itasca, 150 Spring Lake Dr, Itasca, IL, 60143, USA
| | - Sara L. Best
- Labcorp Itasca, 150 Spring Lake Dr, Itasca, IL, 60143, USA
- University of Wisconsin School of Medicine and Public Health, Department of Urology, Madison, WI, USA
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16
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Meder M, Jelley H, Kocolas I, Al-Hamad D. Hypotonia and Poor Weight Gain in a 4-month-old Girl. Pediatr Rev 2024; 45:354-357. [PMID: 38821897 DOI: 10.1542/pir.2021-005379] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Revised: 10/28/2022] [Accepted: 11/08/2022] [Indexed: 06/02/2024]
Affiliation(s)
- Michelle Meder
- University of Utah, Salt Lake City, UT
- Primary Children's Hospital, Salt Lake City, UT
| | - Hannah Jelley
- University of Utah, Salt Lake City, UT
- Primary Children's Hospital, Salt Lake City, UT
| | - Irene Kocolas
- University of Utah, Salt Lake City, UT
- Primary Children's Hospital, Salt Lake City, UT
| | - Dania Al-Hamad
- University of Utah, Salt Lake City, UT
- Primary Children's Hospital, Salt Lake City, UT
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17
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Alsarraf F, Ali DS, Almonaei K, Al-Alwani H, Khan AA, Brandi ML. Hypophosphatasia: presentation and response to asfotase alfa. Osteoporos Int 2024; 35:717-725. [PMID: 37993691 DOI: 10.1007/s00198-023-06943-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/28/2023] [Accepted: 10/04/2023] [Indexed: 11/24/2023]
Abstract
Hypophosphatasia (HPP) is a rare bone disease with limited scientific evidence on the tolerability and safety of its novel treatment, Asfotase Alfa (AA). We report 7 HPP patients' heterogenous presentations and the significant improvement in various clinical outcomes attained with AA shedding light on this highly effective and safe therapy. INTRODUCTION Hypophosphatasia (HPP) is a rare inherited metabolic bone disorder characterized by a deficiency in the tissue non-specific alkaline phosphatase (TNSALP) due to loss of function mutation in the ALPL gene. HPP is associated with impaired skeletal mineralization due to elevations in inorganic pyrophosphate and altered phosphate : pyrophosphate ratio. Asfotase alfa (AA) "enzyme replacement" was approved for treatment of HPP in 2015. We present 7 patients with HPP, 5 with pediatric-onset, and 2 with adult-onset, who have been treated with AA and describe the efficacy and safety in these patients. METHODS 7 patients (4 females, 3 males) aged 19-68 years with HPP were included in this study. Diagnosis of HPP was confirmed by DNA analysis. AA was administered in doses of 6mg/kg/week with a mean follow-up of 6 months (SD= 5). RESULTS Subjective improvement in muscle strength, muscle pain, walking ability, and walking distance with a reduction in the use of gait aids was seen "with AA in HPP patients." Muscle strength and pain improved by up to 70% from baseline as quantified subjectively by patients. Walking distance improved by up to 100%. Patients also reported improved cognition, mood, and energy levels, with up to 90% improvement in mood and 75% improvement in energy levels. 4 out of 6 patients first noted clinical signs of improvement after 3 months of being on therapy. 1 out of the 7 patients sustained a toe fracture 10 months from being on AA. AA was well-tolerated with injection site reactions being the most reported adverse effect. CONCLUSION HPP treatment with AA in individuals with both pediatric and adult-onset forms resulted in significant subjective improvement in musculoskeletal and cognitive manifestations in addition to patients' quality of life. The drug was well tolerated in 6 patients. 1 patient discontinued therapy because of minor adverse effects with myalgias.
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Affiliation(s)
- F Alsarraf
- Division of Endocrinology and Metabolism, McMaster University, Hamilton, Ontario, Canada.
| | - D S Ali
- Division of Endocrinology and Metabolism, McMaster University, Hamilton, Ontario, Canada
| | - K Almonaei
- Department of Endocrinology and Diabetes, Diabetes Treatment Center, Prince Sultan Military Medical City, Riyadh, Saudi Arabia
| | - H Al-Alwani
- Department of Medicine, University of Jeddah, Jeddah, Saudi Arabia
| | - A A Khan
- Division of Endocrinology and Metabolism, McMaster University, Hamilton, Ontario, Canada
| | - M L Brandi
- F.I.R.M.O. Italian Foundation for the Research on Bone Diseases, Florence, Italy
- Donatello Bone Clinic, Villa Donatello Hospital, Florence, Italy
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18
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Zervou Z, Plooij R, van Velsen EFS, Timmermans RGM, Demirdas S, Zillikens MC. Impressive clinical improvement and disappearance of neuropathic pain in an adult patient with hypophosphatasia treated with asfotase alfa. Eur J Med Genet 2024; 68:104915. [PMID: 38325645 DOI: 10.1016/j.ejmg.2024.104915] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Revised: 01/16/2024] [Accepted: 01/28/2024] [Indexed: 02/09/2024]
Abstract
Hypophosphatasia (HPP) is a rare disorder, resulting from loss-of-function variants of the ALPL gene encoding non-tissue specific alkaline phosphatase (TNSALP). Presentation varies largely, with increased severity usually occurring with earlier disease onset. Here we describe the clinical improvement of a 57-year-old woman with childhood onset HPP, after initiating treatment with asfotase alfa (Strensiq®). This was started because of the rapid and progressive radiological deterioration of bone structure after placement of nails in both upper legs for spontaneous atypical femur fracture (AFF) - like fractures. Initiation of treatment, not only resulted in stabilization of bone structure on X-rays, but within a few weeks there was a dramatic reduction of burning pain sensations in the lower legs, attributed in retrospect to neuropathic pain, and also almost complete disappearance of headaches. Additionally, unhealed metatarsal fractures finally healed after almost 10 years. Drug efficacy was further evaluated through -quality of life questionnaires and multiple tests conducted by the physiotherapist, and showed clear improvements. Within 3 months after starting asfotase alfa, the patient was able to carry out her daily tasks indoors without relying on a walker and even started electric bike rides for 20 km/day. In conclusion, treatment with asfotase alfa, halted rapid radiological bone deterioration after bilateral intramedullary femoral pen placement and strongly increased quality of life, marked by rapid disappearance of neuropathic pain, reduction in headaches and musculoskeletal pains, and enhanced muscle strength and mobility. The quick and almost complete disappearance of neuropathic pain and headache suggests a relation with disturbed levels of metabolites in HPP.
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Affiliation(s)
- Zografia Zervou
- Erasmus MC Bone Center, Department of Internal Medicine, Erasmus University Medical Center, Rotterdam, the Netherlands
| | - Roel Plooij
- Erasmus MC, Department of Rehabilitation Medicine, Erasmus University Medical Center, Rotterdam, the Netherlands
| | - Evert F S van Velsen
- Erasmus MC Bone Center, Department of Internal Medicine, Erasmus University Medical Center, Rotterdam, the Netherlands
| | - Remco G M Timmermans
- Erasmus MC, Department of Rehabilitation Medicine, Erasmus University Medical Center, Rotterdam, the Netherlands
| | - Serwet Demirdas
- Department of Clinical Genetics, Sophia Children's Hospital, Erasmus Medical Centre, Erasmus University, Rotterdam, the Netherlands
| | - M Carola Zillikens
- Erasmus MC Bone Center, Department of Internal Medicine, Erasmus University Medical Center, Rotterdam, the Netherlands.
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Whyte MP, Zhang F, Mack KE, Wenkert D, Gottesman GS, Ericson KL, Cole JT, Coburn SP. Pyridoxine challenge reflects pediatric hypophosphatasia severity and thereby examines tissue-nonspecific alkaline phosphatase's role in vitamin B 6 metabolism. Bone 2024; 181:117033. [PMID: 38307176 DOI: 10.1016/j.bone.2024.117033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Revised: 12/28/2023] [Accepted: 01/30/2024] [Indexed: 02/04/2024]
Abstract
Alkaline phosphatase (ALP) is detected in most human tissues. However, ALP activity is routinely assayed using high concentrations of artificial colorimetric substrates in phosphate-free laboratory buffers at lethal pH. Hypophosphatasia (HPP) is the inborn-error-of-metabolism caused by loss-of-function mutation(s) of the ALPL gene that encodes the ALP isoenzyme expressed in bone, liver, kidney, and elsewhere and is therefore designated "tissue-nonspecific" ALP (TNSALP). Consequently, HPP harbors clues concerning the biological function of this phosphohydrolase that is anchored onto the surface of cells. The biochemical signature of HPP features low serum ALP activity (hypophosphatasemia) together with elevated plasma levels of three natural substrates of TNSALP: i) phosphoethanolamine (PEA), a component of the linkage apparatus that binds ALPs and other proteins to the plasma membrane surface; ii) inorganic pyrophosphate (PPi), an inhibitor of bone and tooth mineralization; and iii) pyridoxal 5'-phosphate (PLP), the principal circulating vitameric form of vitamin B6 (B6). Autosomal dominant and autosomal recessive inheritance involving several hundred ALPL mutations underlies the remarkably broad-ranging expressivity of HPP featuring tooth loss often with muscle weakness and rickets or osteomalacia. Thus, HPP associates the "bone" isoform of TNSALP with biomineralization, whereas the physiological role of the "liver", "kidney", and other isoforms of TNSALP remains uncertain. Herein, to examine HPP's broad-ranging severity and the function of TNSALP, we administered an oral challenge of pyridoxine (PN) hydrochloride to 116 children with HPP. We assayed both pre- and post-challenge serum ALP activity and plasma levels of PLP, the B6 degradation product pyridoxic acid (PA), and the B6 vitamer pyridoxal (PL) that can enter cells. Responses were validated by PN challenge of 14 healthy adults and 19 children with metabolic bone diseases other than HPP. HPP severity was assessed using our HPP clinical nosology and patient height Z-scores. PN challenge of all study groups did not alter serum ALP activity in our clinical laboratory. In HPP, both the post-challenge PLP level and the PLP increment correlated (Ps < 0.0001) with the clinical nosology and height Z-scores (Rs = +0.6009 and + 0.4886, and Rs = -0.4846 and - 0.5002, respectively). In contrast, the plasma levels and increments of PA and PL from the PN challenge became less pronounced with HPP severity. We discuss how our findings suggest extraskeletal TNSALP primarily conditioned the PN challenge responses, and explain why they caution against overzealous B6 supplementation of HPP.
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Affiliation(s)
- Michael P Whyte
- Center for Metabolic Bone Disease and Molecular Research, Shriners Hospitals for Children-St Louis, St. Louis, MO 63110, USA; Division of Bone and Mineral Diseases, Department of Internal Medicine, Washington University School of Medicine at Barnes-Jewish Hospital, St. Louis, MO 63110, USA.
| | - Fan Zhang
- Center for Metabolic Bone Disease and Molecular Research, Shriners Hospitals for Children-St Louis, St. Louis, MO 63110, USA.
| | - Karen E Mack
- Center for Metabolic Bone Disease and Molecular Research, Shriners Hospitals for Children-St Louis, St. Louis, MO 63110, USA
| | - Deborah Wenkert
- Center for Metabolic Bone Disease and Molecular Research, Shriners Hospitals for Children-St Louis, St. Louis, MO 63110, USA.
| | - Gary S Gottesman
- Center for Metabolic Bone Disease and Molecular Research, Shriners Hospitals for Children-St Louis, St. Louis, MO 63110, USA; Division of Bone and Mineral Diseases, Department of Internal Medicine, Washington University School of Medicine at Barnes-Jewish Hospital, St. Louis, MO 63110, USA.
| | - Karen L Ericson
- Department of Chemistry and Biochemistry, Purdue University Fort Wayne, Fort Wayne, IN 46805, USA.
| | - Jeffrey T Cole
- Center for Metabolic Bone Disease and Molecular Research, Shriners Hospitals for Children-St Louis, St. Louis, MO 63110, USA.
| | - Stephen P Coburn
- Department of Chemistry and Biochemistry, Purdue University Fort Wayne, Fort Wayne, IN 46805, USA.
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20
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Galetaki DM, Merchant N, Dauber A. Novel therapies for growth disorders. Eur J Pediatr 2024; 183:1121-1128. [PMID: 37831302 DOI: 10.1007/s00431-023-05239-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/18/2023] [Revised: 09/21/2023] [Accepted: 09/22/2023] [Indexed: 10/14/2023]
Abstract
As we continue to understand more about the complex mechanism of growth, a plethora of novel therapies have recently been developed that aim to address barriers and optimize efficacy. This review aims to explore these novel therapies and provide a succinct review based on the latest clinical studies in order to introduce clinicians to therapies that will soon constitute the future in the field of short stature. Conclusion: The review focuses on long-acting growth hormone formulations, a novel growth hormone oral secretagogue, novel treatments for children with achondroplasia, and targeted therapies for rare forms of skeletal dysplasias. What is Known: • Recombinant human growth hormone has been the mainstay of treatment for children with short stature for years. • Such therapy is not always effective based on the underlying diagnosis (e.g achondroplasia, Turner syndrome). Compliance with daily injections is challenging and can directly affect efficacy. What is New: • Recent development of long-acting growth hormone regimens and oral secretagogues can overcome some of these barriers, however several limitations need to be taken into consideration. • Newer therapies for achondroplasia, and other rare forms of skeletal dysplasias introduce us to a new era of targeted therapies for children with short stature. Clinicians ought to be aware of pitfalls and caveats before introducing these novel therapies to every day practice.
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Affiliation(s)
- Despoina M Galetaki
- Division of Endocrinology, Children's National Hospital, Washington, DC, USA
| | - Nadia Merchant
- Division of Endocrinology, Children's National Hospital, Washington, DC, USA
- Department of Pediatrics, George Washington School of Medicine, Washington, DC, USA
| | - Andrew Dauber
- Division of Endocrinology, Children's National Hospital, Washington, DC, USA.
- Department of Pediatrics, George Washington School of Medicine, Washington, DC, USA.
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21
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Baroncelli GI, Carlucci G, Freri E, Giuca MR, Guarnieri V, Navarra G, Toschi B, Mora S. The diagnosis of hypophosphatasia in children as a multidisciplinary effort: an expert opinion. J Endocrinol Invest 2024; 47:739-747. [PMID: 37752373 PMCID: PMC10904512 DOI: 10.1007/s40618-023-02199-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Accepted: 09/12/2023] [Indexed: 09/28/2023]
Abstract
Hypophosphatasia (HPP) is a rare genetic disorder in which pathogenic variants of the ALPL gene lead to a marked decrease of tissue non-specific alkaline phosphatase (TNSALP) activity. Although HPP is a systemic disorder, its clinical manifestations are more evident on bones, teeth, muscle and central nervous system. The clinical spectrum ranges from severe forms with extreme skeletal deformities, respiratory impairment, seizures, to very mild forms with onset in late adulthood and few clinical signs. The diagnosis can be suspected by measurement of TNSALP activity, but the insufficient awareness among health professionals and the lack of official guidelines are responsible for delayed diagnosis in children with HPP. The purpose of the current document is to provide an expert opinion directed at optimizing the diagnostic pathway of pediatric HPP. From April to December 2022, a multidisciplinary working group of 6 experts including two pediatric endocrinologists, a pediatric neurologist, a pediatric odontologist, a clinical geneticist, and a molecular biologist gathered in a series of periodic meetings to discuss the main issues related to the diagnosis of HPP in children and formalize an Expert Opinion statement. The experts agreed on a diagnostic trail that begins with the recognition of specific clinical signs, leading to biochemical analyses of TNSALP activity and vitamin B6 serum concentration. Very important are the neurological and dental manifestation of the disease that should be thoroughly investigated. The evaluation of TNSALP activity must consider sex and age variability and low activity must be persistent. Repeated blood measurements are thus necessary. The molecular analysis is then mandatory to confirm the diagnosis and for genetic counseling.
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Affiliation(s)
- G I Baroncelli
- Pediatric and Adolescent Endocrinology, Division of Pediatrics, Department of Obstetrics, Gynecology and Pediatrics, University Hospital, Pisa, Italy
| | - G Carlucci
- OPT S.P.A., Soluzioni Per Il Mondo Healthcare, Milan, Italy
| | - E Freri
- Department of Pediatric Neuroscience, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - M R Giuca
- Unit of Pediatric Dentistry, Department of Surgical Medical Molecular Pathology and Critical Area, Dental and Oral Surgery Clinic, University of Pisa, Pisa, Italy
| | - V Guarnieri
- Division of Medical Genetics, Fondazione IRCCS Casa Sollievo della Sofferenza, Foggia, Italy
| | - G Navarra
- OPT S.P.A., Soluzioni Per Il Mondo Healthcare, Milan, Italy
| | - B Toschi
- Section of Medical Genetics, Department of Medical and Oncological Area, University Hospital, Pisa, Italy
| | - S Mora
- Laboratory of Pediatric Endocrinology, Department of Pediatrics, IRCCS San Raffaele Hospital, Milan, Italy.
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22
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Aljuraibah F, Alalwan I, Habeb A. Diagnostic and New Therapeutic Approaches to Two Challenging Pediatric Metabolic Bone Disorders: Hypophosphatasia and X-linked Hypophosphatemic Rickets. Curr Pediatr Rev 2024; 20:395-404. [PMID: 37927073 DOI: 10.2174/0115733963206838231031102750] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Revised: 06/09/2023] [Accepted: 10/03/2023] [Indexed: 11/07/2023]
Abstract
The diagnosis and management of metabolic bone disease among children can be challenging. This difficulty could be due to many factors, including limited awareness of these rare conditions, the complex pathophysiology of calcium and phosphate homeostasis, the overlapping phenotype with more common disorders (such as rickets), and the lack of specific treatments for these rare disorders. As a result, affected individuals could experience delayed diagnosis or misdiagnosis, leading to improper management. In this review, we describe the challenges facing diagnostic and therapeutic approaches to two metabolic bone disorders (MBD) among children: hypophosphatasia (HPP) and X-linked hypophosphatemia (XLH). We focus on explaining the pathophysiological processes that conceptually underpin novel therapeutic approaches, as well as these conditions' clinical or radiological similarity to nutritional rickets. Particularly in areas with limited sun exposure and among patients not supplementing vitamin D, nutritional rickets are still more common than HPP and XLH, and pediatricians and primary physicians frequently encounter this disorder in their practices. More recently, our understanding of these disorders has significantly improved, leading to the development of novel therapies. Asfotas alfa, a recombinant, human- tissue, nonspecific alkaline phosphatase, improved the survival of patients with HPP. Burosumab, a human monoclonal anti-FGF23 antibody, was recently approved as a specific therapy for XLH. We also highlight the current evidence on these two specific therapies' safety and effectiveness, though long-term data are still needed. Both HPP and XLH are multisystemic disorders that should be managed by multidisciplinary teams. Finally, recognizing these conditions in early stages will enable affected children and young adults to benefit from newly introduced, specific therapies.
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Affiliation(s)
- Fahad Aljuraibah
- Department of Pediatrics, King Abdullah Specialist Children's Hospital, King Abdulaziz Medical City, Ministry of National Guard Health Affairs, Riyadh, Saudi Arabia
- College of Medicine, King Saud bin Abdul-Aziz University for Health Sciences, Ministry of National Guard Health Affairs, Riyadh, Saudi Arabia
- King Abdullah International Medical Research Center, Ministry of National Guard Health Affairs Riyadh, Saudi Arabia
| | - Ibrahim Alalwan
- Department of Pediatrics, King Abdullah Specialist Children's Hospital, King Abdulaziz Medical City, Ministry of National Guard Health Affairs, Riyadh, Saudi Arabia
- College of Medicine, King Saud bin Abdul-Aziz University for Health Sciences, Ministry of National Guard Health Affairs, Riyadh, Saudi Arabia
- King Abdullah International Medical Research Center, Ministry of National Guard Health Affairs Riyadh, Saudi Arabia
| | - Abdelhadi Habeb
- Department of Pediatrics, Prince Mohammed bin Abdulaziz Hospital for National Guard, Al-Madinah, Saudi Arabia
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23
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Raimann A, Misof BM, Fratzl P, Fratzl-Zelman N. Bone Material Properties in Bone Diseases Affecting Children. Curr Osteoporos Rep 2023; 21:787-805. [PMID: 37897675 DOI: 10.1007/s11914-023-00822-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 09/12/2023] [Indexed: 10/30/2023]
Abstract
PURPOSE OF REVIEW Metabolic and genetic bone disorders affect not only bone mass but often also the bone material, including degree of mineralization, matrix organization, and lacunar porosity. The quality of juvenile bone is moreover highly influenced by skeletal growth. This review aims to provide a compact summary of the present knowledge on the complex interplay between bone modeling and remodeling during skeletal growth and to alert the reader to the complexity of bone tissue characteristics in children with bone disorders. RECENT FINDINGS We describe cellular events together with the characteristics of the different tissues and organic matrix organization (cartilage, woven and lamellar bone) occurring during linear growth. Subsequently, we present typical alterations thereof in disorders leading to over-mineralized bone matrix compared to those associated with low or normal mineral content based on bone biopsy studies. Growth spurts or growth retardation might amplify or mask disease-related alterations in bone material, which makes the interpretation of bone tissue findings in children complex and challenging.
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Affiliation(s)
- Adalbert Raimann
- Department of Pediatrics and Adolescent Medicine, Division of Pediatric Pulmonology, Allergology and Endocrinology, Medical University of Vienna, Vienna, Austria
- Vienna Bone and Growth Center, Vienna, Austria
| | - Barbara M Misof
- Vienna Bone and Growth Center, Vienna, Austria
- Ludwig Boltzmann Institute of Osteology at the Hanusch Hospital of OEGK and AUVA Trauma Center Meidling, 1st Medical Department, Hanusch Hospital, Vienna, Austria
| | - Peter Fratzl
- Max Planck Institute of Colloids and Interfaces, Department of Biomaterials, Research Campus Golm, Potsdam, Germany
| | - Nadja Fratzl-Zelman
- Vienna Bone and Growth Center, Vienna, Austria.
- Ludwig Boltzmann Institute of Osteology at the Hanusch Hospital of OEGK and AUVA Trauma Center Meidling, 1st Medical Department, Hanusch Hospital, Vienna, Austria.
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24
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Hidaka N, Murata H, Tachikawa K, Osaki K, Sekiyama T, Kinoshita Y, Kato H, Hoshino Y, Kimura S, Sunouchi T, Watanabe S, Nangaku M, Makita N, Michigami T, Ito N. The Effect of Asfotase Alfa on Plasma and Urine Pyrophosphate Levels and Pseudofractures in a Patient With Adult-Onset Hypophosphatasia. JBMR Plus 2023; 7:e10842. [PMID: 38130758 PMCID: PMC10731098 DOI: 10.1002/jbm4.10842] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Revised: 10/07/2023] [Accepted: 10/25/2023] [Indexed: 12/23/2023] Open
Abstract
Hypophosphatasia (HPP) is an inherited disease caused by variants of the ALPL gene encoding tissue-nonspecific alkaline phosphatase. Adult-onset HPP (adult HPP), known as a mild form of HPP, develops symptoms involving osteomalacia after the age of 18 years. Asfotase alfa (AA) is a modulated recombinant human alkaline phosphatase (ALP) that has been established as a first-line therapy for severe forms of HPP, such as perinatal and infantile forms. We described a 64-year-old female who presented with pseudofractures in bilateral femur diaphyses and impaired mobility. Low serum ALP activity and a high concentration of urine phosphoethanolamine indicated the diagnosis of HPP, which was confirmed by the identification of a homozygous variant in the ALPL gene (c.319G > A; p.Val107Ile). An in vitro transfection experiment to measure the ALP activity of this novel variant protein was performed, resulting in 40% of the residual enzymatic activity compared with the wild type. AA was initiated to facilitate the union of pseudofracture and to improve mobility. After 6 months, radiographic images revealed the disappearance of fracture lines, and improvement of ambulatory ability was confirmed by the 6-minute walk test (525 to 606 m). The EQ-5D-5L index was also improved (0.757 to 0.895). Within a follow-up period, the levels of urine pyrophosphate corrected by urine creatinine (uPPi/Cre) declined in parallel with the level of plasma PPi (plasma PPi: 6.34 to 1.04 μM, uPPi/Cre: 226.8 to 75.4 nmol/mg). The beneficial effect of AA on pseudofracture healing in adult HPP was presented, although the application of AA should be restricted to patients exhibiting relatively severe manifestations. In addition, a novel pathogenic variant of the ALPL gene was identified with the supportive result of functional analysis. Furthermore, when monitoring patients with HPP treated with AA, uPPi/Cre might be a convenient substitute for plasma PPi, which requires immediate filtration after blood sampling. © 2023 The Authors. JBMR Plus published by Wiley Periodicals LLC. on behalf of American Society for Bone and Mineral Research.
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Affiliation(s)
- Naoko Hidaka
- Division of Nephrology and EndocrinologyThe University of Tokyo HospitalTokyoJapan
- Osteoporosis CenterThe University of Tokyo HospitalTokyoJapan
| | - Hiroaki Murata
- Department of Orthopaedic Surgery, Panasonic Health Insurance OrganizationMatsushita Memorial HospitalOsakaJapan
| | - Kanako Tachikawa
- Department of Bone and Mineral Research, Research InstituteOsaka Women's and Children's HospitalOsakaJapan
| | - Keiichi Osaki
- Department of Rehabilitation, Panasonic Health Insurance OrganizationMatsushita Memorial HospitalOsakaJapan
| | - Takashi Sekiyama
- Department of Rehabilitation, Panasonic Health Insurance OrganizationMatsushita Memorial HospitalOsakaJapan
| | - Yuka Kinoshita
- Division of Nephrology and EndocrinologyThe University of Tokyo HospitalTokyoJapan
- Osteoporosis CenterThe University of Tokyo HospitalTokyoJapan
| | - Hajime Kato
- Division of Nephrology and EndocrinologyThe University of Tokyo HospitalTokyoJapan
- Osteoporosis CenterThe University of Tokyo HospitalTokyoJapan
| | - Yoshitomo Hoshino
- Division of Nephrology and EndocrinologyThe University of Tokyo HospitalTokyoJapan
- Osteoporosis CenterThe University of Tokyo HospitalTokyoJapan
| | - Soichiro Kimura
- Division of Nephrology and EndocrinologyThe University of Tokyo HospitalTokyoJapan
- Osteoporosis CenterThe University of Tokyo HospitalTokyoJapan
| | - Takashi Sunouchi
- Division of Nephrology and EndocrinologyThe University of Tokyo HospitalTokyoJapan
- Osteoporosis CenterThe University of Tokyo HospitalTokyoJapan
| | - So Watanabe
- Osteoporosis CenterThe University of Tokyo HospitalTokyoJapan
- Department of Geriatric Medicine, Graduate School of MedicineThe University of TokyoTokyoJapan
| | - Masaomi Nangaku
- Division of Nephrology and EndocrinologyThe University of Tokyo HospitalTokyoJapan
| | - Noriko Makita
- Division of Nephrology and EndocrinologyThe University of Tokyo HospitalTokyoJapan
- Osteoporosis CenterThe University of Tokyo HospitalTokyoJapan
| | - Toshimi Michigami
- Department of Bone and Mineral Research, Research InstituteOsaka Women's and Children's HospitalOsakaJapan
| | - Nobuaki Ito
- Division of Nephrology and EndocrinologyThe University of Tokyo HospitalTokyoJapan
- Osteoporosis CenterThe University of Tokyo HospitalTokyoJapan
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25
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Fratzl-Zelman N, Linglart A, Bin K, Rauch F, Blouin S, Coutant R, Donzeau A. Combination of osteogenesis imperfecta and hypophosphatasia in three children with multiple fractures, low bone mass and severe osteomalacia, a challenge for therapeutic management. Eur J Med Genet 2023; 66:104856. [PMID: 37758163 DOI: 10.1016/j.ejmg.2023.104856] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Revised: 09/05/2023] [Accepted: 09/24/2023] [Indexed: 10/03/2023]
Abstract
Osteogenesis imperfecta (OI) and hypophosphatasia (HPP) are rare skeletal disorders caused by mutations in the genes encoding collagen type I (COL1A, COL1A2) and tissue-non-specific isoenzyme of alkaline phosphatase (ALPL), respectively. Both conditions result in skeletal deformities and bone fragility although bone tissue abnormalities differ considerably. Children with OI have low bone mass and hypermineralized matrix, whereas HPP children develop rickets and osteomalacia. We report a family, father and three children, affected with growth retardation, low bone mass and recurrent fractures. None of them had rickets, blue sclera or dentinogenesis imperfecta. ALP serum levels were low and genetics revealed in the four probands heterozygous pathogenic mutations in COL1A2 c.838G > A (p.Gly280Ser) and in ALPL c.1333T > C (p.Ser445Pro). After multidisciplinary meeting, a diagnostic transiliac bone biopsy was indicated for each sibling for therapeutic decision. Bone histology and histomorphometry, as compared to reference values of children with OI type I as well as, to a control pediatric patient harboring the same COL1A2 mutation, revealed similarly decreased trabecular bone volume, increased osteocyte lacunae, but additionally severe osteomalacia. Quantitative backscattered electron imaging demonstrated that bone matrix mineralization was not as decreased as expected for osteomalacia. In summary, we observed within each biopsy samples classical features of OI and classical features of HPP. The apparent nearly normal bone mineralization density distribution results presumably from divergent effects of OI and HPP on matrix mineralization. A combination therapy was initiated with ALP enzyme-replacement and one month later with bisphosphonates. The ongoing treatment led to improved skeletal growth, increased BMD and markedly reduced fracture incidence.
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Affiliation(s)
- Nadja Fratzl-Zelman
- Ludwig Boltzmann Institute of Osteology at Hanusch Hospital of OEGK and AUVA Trauma Centre Meidling, 1st Med. Department Hanusch Hospital, Vienna, Austria; Vienna Bone and Growth Center, Vienna, Austria.
| | - Agnès Linglart
- AP-HP, Paris Saclay University, INSERM, Reference Center for Rare Diseases of the Calcium and Phosphate Metabolism, Platform of Expertise for Rare Diseases, OSCAR Filière, EndoERN and BOND ERN Center, Endocrinology and Diabetes for Children, Bicêtre Paris Saclay Hospital, France
| | - Kim Bin
- Pediatric Orthopedic Surgery Angers University Hospital, Angers, France
| | - Frank Rauch
- Shriners Hospital for Children, Canada, Montreal, QC, Canada
| | - Stéphane Blouin
- Ludwig Boltzmann Institute of Osteology at Hanusch Hospital of OEGK and AUVA Trauma Centre Meidling, 1st Med. Department Hanusch Hospital, Vienna, Austria; Vienna Bone and Growth Center, Vienna, Austria
| | - Régis Coutant
- AP-HP, Paris Saclay University, INSERM, Reference Center for Rare Diseases of the Calcium and Phosphate Metabolism, Platform of Expertise for Rare Diseases, OSCAR Filière, EndoERN and BOND ERN Center, Endocrinology and Diabetes for Children, Bicêtre Paris Saclay Hospital, France; Department of Pediatric Endocrinology and Diabetology, Competence Center for Rare Diseases of the Calcium and Phosphate Metabolism, Angers University Hospital, Angers, France
| | - Aurélie Donzeau
- Department of Pediatric Endocrinology and Diabetology, Competence Center for Rare Diseases of the Calcium and Phosphate Metabolism, Angers University Hospital, Angers, France
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26
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Kim EN, Leung KL, Wong A, McGregor J, Skolnick GB, Patel KB, Gosman AA. Management of Craniosynostosis in Lethal Perinatal Hypophosphatasia. J Craniofac Surg 2023; 34:2422-2425. [PMID: 37610006 DOI: 10.1097/scs.0000000000009641] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Accepted: 06/11/2023] [Indexed: 08/24/2023] Open
Abstract
Although perinatal lethal hypophosphatasia (HPP) was once a disease with a universally poor prognosis, it has now become a rare but treatable condition with the advent of enzyme replacement therapy with asfotase alfa. As a result, a greater population of patients with perinatal HPP are presenting with abnormal head shape and craniosynostosis. The authors present here 3 cases of perinatal lethal HPP, 1 treated with traditional open cranial vault remodeling and 2 treated utilizing distraction osteogenesis techniques. All patients demonstrated outcomes comparable to those previously reported with traditional observation or open cranial vault repair. Thorough consideration and discussion between the surgical team and patient's family is needed to determine a treatment plan that best addresses the goals of patient and family in light of recent advances in medical treatment in this rare patient population in which surgical interventions were previously nearly impossible. This article further supports the safety and efficacy of surgical intervention and explores the utility of distraction osteogenesis to address craniosynostosis in this patient population.
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Affiliation(s)
- Erinn N Kim
- Division of Plastic Surgery, University of California San Diego, San Diego, CA
| | - Karen L Leung
- Division of Plastic Surgery, University of California San Diego, San Diego, CA
| | - Alvin Wong
- Division of Plastic Surgery, Virginia Commonwealth University, Richmond, VA
| | - Jyoti McGregor
- Section of Plastic Surgery, University of Mannitoba, Winnipeg, MB, Canada
| | - Gary B Skolnick
- Division of Plastic Surgery, Washington University, St. Louis, MO
| | - Kamlesh B Patel
- Division of Plastic Surgery, Washington University, St. Louis, MO
| | - Amanda A Gosman
- Division of Plastic Surgery, University of California San Diego, San Diego, CA
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27
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Nair SC, Al-Dahmani KM. The Development of a Clinical Research Model Complementing Medical Residency and the Assessment of Research Productivity. Cureus 2023; 15:e48684. [PMID: 38090409 PMCID: PMC10714375 DOI: 10.7759/cureus.48684] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/10/2023] [Indexed: 01/24/2024] Open
Abstract
BACKGROUND AND OBJECTIVE Despite modern healthcare infrastructure, there is a paucity of information about the clinical research framework supporting healthcare in the United Arab Emirates (UAE). Therefore, this study aimed to assess research performance productivity, and the clinical research framework, complementing medical residency, at the nation's hub for clinical research. METHODS A cross-sectional retrospective review of records from the research database of the institution was conducted to assess productivity, and framework development, and data analyzed. RESULTS The migration of global healthcare providers, and the pharmaceutical industry offices, the adoption of the International Conference on Harmonization (ICH) guidelines, and electronic medical records established a research culture. Following the development of the governance framework, a total of 1,328 research projects were submitted to the ethics committee until 2023. Approximately 63% of the total studies were of minimal risk, followed by industry-sponsored clinical trials (4.9%, 58/1,163), and prospective interventional studies (3.5%, 39/1,163). Almost half (48.3%, 28/58) of the total industry-sponsored clinical trials were phase II and phase III. The number of peer-reviewed indexed publications, a measure of research productivity, indicated that the periods between 2011 and 2015, 2016 and 2020, and 2021 and 2023 witnessed a 3.8-, 9.3-, and 7.9-fold increase compared to the baseline period (1995-2005). The implementation of the Focus on International Research Strategy, Teaching, Evaluation, and Mentoring (FIRSTEM) strategy, to accommodate mandatory research activity requirements for residents by the physician licensing boards, observed substantial increases in output. The number of international peer-reviewed indexed publications/resident projects doubled from 10.8% (2010-2015) to 24% (2016-2020) and reached 40.1% in 2023. CONCLUSION This is the first research governance model established in the UAE, a country with an increasing prevalence of diabetes, and cardiovascular and genetic diseases. The model indicates that the medical trainees differentiate the best research evidence in making decisions about the clinical care of patients. The study outcomes may potentially be useful for other countries in developing a clinical research framework.
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Affiliation(s)
- Satish C Nair
- Medical Research, Johns Hopkins Medicine International, Tawam Hospital, Al Ain, ARE
| | - Khaled M Al-Dahmani
- Diabetes and Endocrinology, Johns Hopkins Medicine International, Tawam Hospital, Al Ain, ARE
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28
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Seefried L, Genest F, Petryk A, Veith M. Effects of asfotase alfa in adults with pediatric-onset hypophosphatasia over 24 months of treatment. Bone 2023; 175:116856. [PMID: 37481150 DOI: 10.1016/j.bone.2023.116856] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Revised: 06/30/2023] [Accepted: 07/19/2023] [Indexed: 07/24/2023]
Abstract
BACKGROUND Hypophosphatasia (HPP) is a rare, heritable metabolic disorder caused by deficient activity of tissue-nonspecific alkaline phosphatase (TNSALP). Asfotase alfa (AA) is a human recombinant TNSALP that promotes bone mineralization and is approved to treat eligible patients with HPP. METHODS This prospective single-center observational study evaluated AA in adults with pediatric-onset HPP over 2 years of treatment (ClinicalTrials.govNCT03418389). Primary outcomes evaluated physical function; secondary outcomes assessed quality of life (QoL) and pain. RESULTS The study included 17 females and 5 males (mean age: 48.7 years). Median distance walked in the 6-Minute Walk Test increased significantly from baseline to 12 months (P = 0.034) and results were sustained. Median Timed Up and Go test time significantly decreased from baseline at 12 (P = 0.003) and 24 months (P = 0.005), as did the median chair rise time test at 12 (P = 0.003) and 24 months (P < 0.002). The change from baseline in usual gait speed was significant at 12 (P = 0.003) and 24 months (P = 0.015). Mean dominant and nondominant hand grip strength improved at 24 months (P = 0.029 and P = 0.019, respectively). Median Short Form 36 Physical Component Summary scores significantly improved from baseline at 12 (P = 0.012) and 24 (P = 0.005) months, and median Lower Extremity Functional Scale scores improved from baseline at 12 (P = 0.001) and 24 (P = 0.002) months. No significant change was noted in pain level at these timepoints. While injection site reactions occurred in 86.4 % of the participants, there were no severe side effects or safety findings. CONCLUSIONS Adults with pediatric-onset HPP treated with AA experienced marked improvement in functional and QoL outcomes that were observed as early as within 3 months of initial treatment and were sustained over 24 months.
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Affiliation(s)
- Lothar Seefried
- Osteology Department, Julius-Maximilians-Universität Würzburg, Würzburg, Germany.
| | - Franca Genest
- Osteology Department, Julius-Maximilians-Universität Würzburg, Würzburg, Germany
| | - Anna Petryk
- Department of Global Medical Affairs, Alexion, AstraZeneca Rare Disease, Boston, MA, USA
| | - Marina Veith
- Osteology Department, Julius-Maximilians-Universität Würzburg, Würzburg, Germany
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29
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Pontán F, Hauta-Alus H, Valkama S, Rosendahl J, Enlund-Cerullo M, Andersson S, Mäkitie O, Holmlund-Suila E. Alkaline Phosphatase and Hyperphosphatasemia in Vitamin D Trial in Healthy Infants and Toddlers. J Clin Endocrinol Metab 2023; 108:e1082-e1091. [PMID: 37061810 DOI: 10.1210/clinem/dgad208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Revised: 03/16/2023] [Accepted: 04/12/2023] [Indexed: 04/17/2023]
Abstract
CONTEXT Childhood hyperphosphatasemia is usually transient and may be associated with infections. It remains less well known how hyperphosphatasemia is related to growth and bone mineralization. OBJECTIVE We explored alkaline phosphatase (ALP) concentrations and prevalence of hyperphosphatasemia, and their association with vitamin D, growth, infections, and bone parameters in healthy children. METHODS The study was a secondary analysis of a vitamin D intervention trial. Participants received vitamin D3 10 or 30 µg daily from age 2 weeks to 2 years. Children with data on ALP at 12 and/or 24 months (n = 813, girls 51.9%) were included. Anthropometrics and bone parameters were measured at 12 and 24 months. Infections were recorded prospectively by the parents. RESULTS Boys had higher ALP than girls at 12 months (median [IQR] 287 [241-345] U/L vs 266 [218-341] U/L; P = .02). At 24 months concentrations were lower than at 12 months (240 [202-284]; P < .001) but without sex difference. The prevalence of hyperphosphatasemia (ALP > 1000 U/L) at 12 months was 5.3% and at 24 months 0.6%. Body size, growth rate, and bone mineral content associated positively with ALP, while vitamin D intervention had no effect. Infants with hyperphosphatasemia were smaller than infants with ALP ≤ 1000 U/L. Hyperphosphatasemia was not associated with previous infections. CONCLUSION Approximately 5% of infants had hyperphosphatasemia at 12 months, but <1% at 24 months. ALP concentrations and hyperphosphatasemia were associated with sex, anthropometry, and bone mineralization. Infections did not contribute to hyperphosphatasemia.
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Affiliation(s)
- Freja Pontán
- Children's Hospital, Pediatric Research Center, University of Helsinki and Helsinki University Hospital, 00029 Helsinki, Finland
| | - Helena Hauta-Alus
- Children's Hospital, Pediatric Research Center, University of Helsinki and Helsinki University Hospital, 00029 Helsinki, Finland
- Research Program for Clinical and Molecular Metabolism, Faculty of Medicine, University of Helsinki, 00014 Helsinki, Finland
- Population Health Unit, Finnish Institute for Health and Welfare (THL), 00300 Helsinki, Finland
- Clinical Medicine Research Unit, Medical Research Center Oulu, Oulu University Hospital and University of Oulu, 90014 Oulu, Finland
| | - Saara Valkama
- Children's Hospital, Pediatric Research Center, University of Helsinki and Helsinki University Hospital, 00029 Helsinki, Finland
- Research Program for Clinical and Molecular Metabolism, Faculty of Medicine, University of Helsinki, 00014 Helsinki, Finland
| | - Jenni Rosendahl
- Children's Hospital, Pediatric Research Center, University of Helsinki and Helsinki University Hospital, 00029 Helsinki, Finland
- Research Program for Clinical and Molecular Metabolism, Faculty of Medicine, University of Helsinki, 00014 Helsinki, Finland
| | - Maria Enlund-Cerullo
- Children's Hospital, Pediatric Research Center, University of Helsinki and Helsinki University Hospital, 00029 Helsinki, Finland
- Research Program for Clinical and Molecular Metabolism, Faculty of Medicine, University of Helsinki, 00014 Helsinki, Finland
- Institute of Genetics, Folkhälsan Research Center, 00290 Helsinki, Finland
| | - Sture Andersson
- Children's Hospital, Pediatric Research Center, University of Helsinki and Helsinki University Hospital, 00029 Helsinki, Finland
| | - Outi Mäkitie
- Children's Hospital, Pediatric Research Center, University of Helsinki and Helsinki University Hospital, 00029 Helsinki, Finland
- Research Program for Clinical and Molecular Metabolism, Faculty of Medicine, University of Helsinki, 00014 Helsinki, Finland
- Institute of Genetics, Folkhälsan Research Center, 00290 Helsinki, Finland
- Department of Molecular Medicine and Surgery, Karolinska Institutet, 171 77 Stockholm, Sweden
- Department of Clinical Genetics, Karolinska University Hospital, 171 77 Stockholm, Sweden
| | - Elisa Holmlund-Suila
- Children's Hospital, Pediatric Research Center, University of Helsinki and Helsinki University Hospital, 00029 Helsinki, Finland
- Research Program for Clinical and Molecular Metabolism, Faculty of Medicine, University of Helsinki, 00014 Helsinki, Finland
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Smart G, Jensen ED, Poirier BF, Sethi S. The impact of enzyme replacement therapy on the oral health manifestations of hypophosphatasia among children: a scoping review. Eur Arch Paediatr Dent 2023; 24:429-440. [PMID: 37036643 DOI: 10.1007/s40368-023-00796-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Accepted: 03/22/2023] [Indexed: 04/11/2023]
Abstract
PURPOSE A scoping review to describe the use of enzyme replacement therapy (ERT) in the form of asfotase alfa to decrease the severity of oral manifestations in children with hypophosphatasia (HPP). METHODS Six databases were searched using keywords and index terms related to "hypophosphatasia," "children," and "enzyme replacement therapy." Duplicates were removed and two independent reviewers screened the titles and abstracts to identify articles for full-text review. Extracted data was summarised narratively. RESULTS The systematic search identified 3548 articles, with 171 suitable for full-text review and a final 22 that met inclusion criteria. Enzyme replacement therapy generally resulted in a reduction in the presence and severity of oral manifestations of HPP. However, numerous studies failed to report specific details regarding the nature of oral health outcomes and there were reported cases of further loss of primary teeth. CONCLUSIONS The available evidence suggests that that ERT in the form of asfotase alfa for HPP in infants and young children leads to improved oral health outcomes. It is recommended that the outcomes are improved with earlier initiation of ERT. Further, well-designed clinical research is required to assess oral health improvements and decreased morbidity associated with the early loss of teeth.
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Affiliation(s)
- G Smart
- Department of Paediatric Dentistry, Women's and Children's Hospital, 72 King William Road, North Adelaide, SA, 5006, Australia.
| | - E D Jensen
- Department of Paediatric Dentistry, Women's and Children's Hospital, 72 King William Road, North Adelaide, SA, 5006, Australia
- Adelaide Dental School, The University of Adelaide, Adelaide, SA, Australia
| | - B F Poirier
- Adelaide Dental School, The University of Adelaide, Adelaide, SA, Australia
| | - S Sethi
- Adelaide Dental School, The University of Adelaide, Adelaide, SA, Australia
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Yu Y, Rong K, Yao D, Zhang Q, Cao X, Rao B, Xia Y, Lu Y, Shen Y, Yao Y, Xu H, Ma P, Cao Y, Qin A. The structural pathology for hypophosphatasia caused by malfunctional tissue non-specific alkaline phosphatase. Nat Commun 2023; 14:4048. [PMID: 37422472 PMCID: PMC10329691 DOI: 10.1038/s41467-023-39833-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Accepted: 06/30/2023] [Indexed: 07/10/2023] Open
Abstract
Hypophosphatasia (HPP) is a metabolic bone disease that manifests as developmental abnormalities in bone and dental tissues. HPP patients exhibit hypo-mineralization and osteopenia due to the deficiency or malfunction of tissue non-specific alkaline phosphatase (TNAP), which catalyzes the hydrolysis of phosphate-containing molecules outside the cells, promoting the deposition of hydroxyapatite in the extracellular matrix. Despite the identification of hundreds of pathogenic TNAP mutations, the detailed molecular pathology of HPP remains unclear. Here, to address this issue, we determine the crystal structures of human TNAP at near-atomic resolution and map the major pathogenic mutations onto the structure. Our study reveals an unexpected octameric architecture for TNAP, which is generated by the tetramerization of dimeric TNAPs, potentially stabilizing the TNAPs in the extracellular environments. Moreover, we use cryo-electron microscopy to demonstrate that the TNAP agonist antibody (JTALP001) forms a stable complex with TNAP by binding to the octameric interface. The administration of JTALP001 enhances osteoblast mineralization and promoted recombinant TNAP-rescued mineralization in TNAP knockout osteoblasts. Our findings elucidate the structural pathology of HPP and highlight the therapeutic potential of the TNAP agonist antibody for osteoblast-associated bone disorders.
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Affiliation(s)
- Yating Yu
- Department of Orthopedics, Shanghai Key Laboratory of Orthopedics Implant, the Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
- Institute of Precision Medicine, the Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, 115 Jinzun Road, Shanghai, 200125, China
| | - Kewei Rong
- Department of Orthopedics, Shanghai Key Laboratory of Orthopedics Implant, the Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
| | - Deqiang Yao
- State Key Laboratory of Oncogenes and Related Genes, Ren Ji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200127, China
| | - Qing Zhang
- Department of Orthopedics, Shanghai Key Laboratory of Orthopedics Implant, the Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
- Institute of Precision Medicine, the Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, 115 Jinzun Road, Shanghai, 200125, China
| | - Xiankun Cao
- Department of Orthopedics, Shanghai Key Laboratory of Orthopedics Implant, the Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
| | - Bing Rao
- Department of Orthopedics, Shanghai Key Laboratory of Orthopedics Implant, the Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China
- Institute of Precision Medicine, the Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, 115 Jinzun Road, Shanghai, 200125, China
| | - Ying Xia
- Institute of Precision Medicine, the Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, 115 Jinzun Road, Shanghai, 200125, China
| | - Yi Lu
- Institute of Precision Medicine, the Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, 115 Jinzun Road, Shanghai, 200125, China
| | - Yafeng Shen
- Institute of Precision Medicine, the Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, 115 Jinzun Road, Shanghai, 200125, China
| | - Ying Yao
- Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, Shanghai, 201210, China
| | - Hongtao Xu
- Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, Shanghai, 201210, China
| | - Peixiang Ma
- Department of Orthopedics, Shanghai Key Laboratory of Orthopedics Implant, the Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China.
| | - Yu Cao
- Department of Orthopedics, Shanghai Key Laboratory of Orthopedics Implant, the Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China.
- Institute of Precision Medicine, the Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, 115 Jinzun Road, Shanghai, 200125, China.
| | - An Qin
- Department of Orthopedics, Shanghai Key Laboratory of Orthopedics Implant, the Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200011, China.
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Reis FS, Lazaretti-Castro M. Hypophosphatasia: from birth to adulthood. ARCHIVES OF ENDOCRINOLOGY AND METABOLISM 2023; 67:e000626. [PMID: 37249457 PMCID: PMC10665056 DOI: 10.20945/2359-3997000000626] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Accepted: 12/12/2022] [Indexed: 05/31/2023]
Abstract
Hypophosphatasia (HPP) is an inherited disease caused by a low activity of tissue-nonspecific alkaline phosphatase, a hydrolase that removes phosphate groups from many molecules. Decreased alkaline phosphatase activity leads to the accumulation of three main metabolites, i.e., pyridoxal 5´-phosphate (PLP), inorganic pyrophosphate (PPi), and phosphoethanolamine. Impairment in PLP dephosphorylation induces seizures, while PPi accumulation inhibits bone mineralization. Clinically, HPP has a wide spectrum of presentations, ranging from neonatal death to an apparent lack of symptoms. This disease is classified into six subtypes according to the age at onset of first signs or symptoms. The clinical manifestations of the disease include rickets-like bone changes, bone demineralization, fragility fractures, reduced muscular strength, chest deformity, pulmonary hypoplasia, nephrolithiasis, nephrocalcinosis, and chondrocalcinosis. Treatment of HPP consists of enzyme replacement therapy. Before this therapy was approved, treatment was palliative and associated with high morbidity and mortality. Asfotase alfa has changed the prognosis of the disease by reducing bone deformity and improving bone mineralization, lung function, and muscle weakness, among other benefits. In adults, teriparatide and anti-sclerostin antibody have been used off-label in selected cases, demonstrating benefit in accelerating fracture healing and in concomitant treatment of osteoporosis. This review summarizes the main aspects of HPP and identifies the particularities of the disease in adult patients.
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Affiliation(s)
- Fernanda Salles Reis
- Departamento de Medicina, Disciplina de Endocrinologia, Universidade Federal de São Paulo (Unifesp), São Paulo, Brasil
| | - Marise Lazaretti-Castro
- Departamento de Medicina, Disciplina de Endocrinologia, Universidade Federal de São Paulo (Unifesp), São Paulo, Brasil,
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Riancho JA. Diagnostic Approach to Patients with Low Serum Alkaline Phosphatase. Calcif Tissue Int 2023; 112:289-296. [PMID: 36348061 DOI: 10.1007/s00223-022-01039-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Accepted: 10/26/2022] [Indexed: 11/09/2022]
Abstract
Increased serum levels of alkaline phosphatase (ALP) are widely recognized as a biochemical marker of many disorders affecting the liver or bone. However, the approach for patients with low ALP phosphatase is not well-established. Low serum ALP is an epiphenomenon of many severe acute injuries and diseases. Persistently low serum ALP may be secondary to drug therapy (including antiresorptives) or a variety of acquired disorders, such as malnutrition, vitamin and mineral deficiencies, endocrine disorders, etc. Hypophosphatasia, due to pathogenic variants of the ALPL gene, which encodes tissue non-specific ALP, is the most common genetic cause of low serum ALP. Marked bone hypomineralization is frequent in severe pediatric-onset cases. However, adult forms of hypophosphatasia usually present with milder manifestations, such as skeletal pain, chondrocalcinosis, calcific periarthritis, dental problems, and stress fractures. The diagnostic approach to these patients is discussed. Measuring several ALP substrates, such as pyrophosphate, pyridoxal phosphate, or phosphoethanolamine, may help to establish enzyme deficiency. Gene analysis showing a pathogenic variant in ALPL may confirm the diagnosis. However, a substantial proportion of patients show normal results after sequencing ALPL exons. It is still unknown if those patients carry unidentified mutations in regulatory regions of ALPL, epigenetic changes, or abnormalities in other genes.
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Affiliation(s)
- Jose A Riancho
- Departamento de Medicina y Psiquiatría, Universidad de Cantabria, Servicio de Medicina Interna, Hospital UM Valdecilla-IDIVAL, Av Valdecilla sn, 39008, Santander, Spain.
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Wölfel EM, von Kroge S, Matthies L, Koehne T, Petz K, Beikler T, Schmid-Herrmann CU, Kahl-Nieke B, Tsiakas K, Santer R, Muschol NM, Herrmann J, Busse B, Amling M, Rolvien T, Jandl NM, Barvencik F. Effects of Infantile Hypophosphatasia on Human Dental Tissue. Calcif Tissue Int 2023; 112:308-319. [PMID: 36414794 PMCID: PMC9968273 DOI: 10.1007/s00223-022-01041-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Accepted: 11/02/2022] [Indexed: 11/23/2022]
Abstract
Hypophosphatasia (HPP) is an inherited, systemic disorder, caused by loss-of-function variants of the ALPL gene encoding the enzyme tissue non-specific alkaline phosphatase (TNSALP). HPP is characterized by low serum TNSALP concentrations associated with defective bone mineralization and increased fracture risk. Dental manifestations have been reported as the exclusive feature (odontohypophosphatasia) and in combination with skeletal complications. Enzyme replacement therapy (asfotase alfa) has been shown to improve respiratory insufficiency and skeletal complications in HPP patients, while its effects on dental status have been understudied to date. In this study, quantitative backscattered electron imaging (qBEI) and histological analysis were performed on teeth from two patients with infantile HPP before and during asfotase alfa treatment and compared to matched healthy control teeth. qBEI and histological methods revealed varying mineralization patterns in cementum and dentin with lower mineralization in HPP. Furthermore, a significantly higher repair cementum thickness was observed in HPP compared to control teeth. Comparison before and during treatment showed minor improvements in mineralization and histological parameters in the patient when normalized to matched control teeth. HPP induces heterogeneous effects on mineralization and morphology of the dental status. Short treatment with asfotase alfa slightly affects mineralization in cementum and dentin. Despite HPP being a rare disease, its mild form occurs at higher prevalence. This study is of high clinical relevance as it expands our knowledge of HPP and dental involvement. Furthermore, it contributes to the understanding of dental tissue treatment, which has hardly been studied so far.
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Affiliation(s)
- Eva Maria Wölfel
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestr. 59, 22529, Hamburg, Germany
- Interdisciplinary Competence Center for Interface Research (ICCIR), Lottestr. 55A, Hamburg, Germany
| | - Simon von Kroge
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestr. 59, 22529, Hamburg, Germany
| | - Levi Matthies
- Department of Oral and Maxillofacial Surgery, University Medical Center Hamburg-Eppendorf, Martinistr. 52, 20246, Hamburg, Germany
| | - Till Koehne
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestr. 59, 22529, Hamburg, Germany
- Department of Orthodontics, Center for Dental and Oral Medicine, University Medical Center Hamburg-Eppendorf, Martinistr. 52, 20246, Hamburg, Germany
| | - Karin Petz
- Department of Periodontics, Preventive and Restorative Dentistry, University Medical Center Hamburg-Eppendorf, Martinistr. 52, 20246, Hamburg, Germany
| | - Thomas Beikler
- Department of Periodontics, Preventive and Restorative Dentistry, University Medical Center Hamburg-Eppendorf, Martinistr. 52, 20246, Hamburg, Germany
| | - Carmen Ulrike Schmid-Herrmann
- Department of Orthodontics, Center for Dental and Oral Medicine, University Medical Center Hamburg-Eppendorf, Martinistr. 52, 20246, Hamburg, Germany
| | - Bärbel Kahl-Nieke
- Department of Orthodontics, Center for Dental and Oral Medicine, University Medical Center Hamburg-Eppendorf, Martinistr. 52, 20246, Hamburg, Germany
| | - Konstantinos Tsiakas
- Department of Pediatrics, University Medical Center Hamburg-Eppendorf, Martinistr. 52, 20246, Hamburg, Germany
| | - René Santer
- Department of Pediatrics, University Medical Center Hamburg-Eppendorf, Martinistr. 52, 20246, Hamburg, Germany
| | - Nicole Maria Muschol
- Department of Pediatrics, University Medical Center Hamburg-Eppendorf, Martinistr. 52, 20246, Hamburg, Germany
| | - Jochen Herrmann
- Department of Diagnostic and Interventional Radiology and Nuclear Medicine, Section of Pediatric Radiology, University Medical Center Hamburg-Eppendorf, Martinistr. 52, 20246, Hamburg, Germany
| | - Björn Busse
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestr. 59, 22529, Hamburg, Germany
- Interdisciplinary Competence Center for Interface Research (ICCIR), Lottestr. 55A, Hamburg, Germany
| | - Michael Amling
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestr. 59, 22529, Hamburg, Germany
| | - Tim Rolvien
- Division of Orthopaedics, Department of Trauma and Orthopaedic Surgery, University Medical Center Hamburg-Eppendorf, Martinistr. 52, 20246, Hamburg, Germany
| | - Nico Maximilian Jandl
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestr. 59, 22529, Hamburg, Germany
- Division of Orthopaedics, Department of Trauma and Orthopaedic Surgery, University Medical Center Hamburg-Eppendorf, Martinistr. 52, 20246, Hamburg, Germany
| | - Florian Barvencik
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestr. 59, 22529, Hamburg, Germany.
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Kim I, Noh ES, Kim MS, Jang JH, Jeon TY, Choi HW, Cho SY. Six-year clinical outcomes of enzyme replacement therapy for perinatal lethal and infantile hypophosphatasia in Korea: Two case reports. Medicine (Baltimore) 2023; 102:e32800. [PMID: 36820543 PMCID: PMC9907957 DOI: 10.1097/md.0000000000032800] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/12/2023] Open
Abstract
INTRODUCTION Hypophosphatasia (HPP) is a genetic disease caused by loss-of-function mutations in ALPL, which encodes tissue-nonspecific alkaline phosphatase (ALP). Early diagnosis and treatment of perinatal and infantile HPP are important because of their high mortality rates. Enzyme replacement therapy (ERT) using human recombinant tissue-nonspecific ALP asfotase alfa was introduced in Korea in 2016. We report the first experience of ERT over 6 years for perinatal lethal and infantile HPP in Korea. PATIENT CONCERNS The first patient was a 6-week-old Korean boy with a failure to thrive. The second patient was an 8-day-old Korean-Uzbek body with generalized tonic-clonic seizure with cyanosis. DIAGNOSES HPP was suspected in both patients because of the very low level of ALP activity and rachitic findings on radiographs, and the disease was confirmed by Sanger sequencing of the ALPL gene. INTERVENTION The first patient with infantile HPP started ERT at 21 months of age and the second patient with perinatal HPP started ERT at 30 days of age. Both patients received asfotase alfa (2 mg/kg 3 times per week subcutaneously, adjusted to 3 mg/kg 3 times per week if required) for 6 years. OUTCOMES After 6 years of ERT, radiographic findings and growth standard deviation scores improved in both patients. The second patient showed no evidence of rickets after 3 years of ERT. Mechanical respiratory support and supplemental oxygen were not required after 4.5 years of treatment in the first patient and at 2 months after treatment in the second patient. CONCLUSION Among the 2 patients, the patient who started ERT early had a much better prognosis despite a more severe initial clinical presentation. Our results suggest that early diagnosis and prompt treatment play an important role in improving long-term prognosis and avoiding morbidity and premature mortality in patients with perinatal and infantile HPP.
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Affiliation(s)
- Insung Kim
- Department of Public Health Administration, Asan City Health Center, Asan, Korea
| | - Eu-Seon Noh
- Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Min-Sun Kim
- Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Ja-Hyun Jang
- Department of Laboratory Medicine and Genetics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Tae Yeon Jeon
- Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Hae Won Choi
- Department of Orthodontics, The Institute of Oral Health Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Sung Yoon Cho
- Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
- * Correspondence: Sung Yoon Cho, Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University School of Medicine, 81 Irwon-ro, Gangnam-gu, Seoul 06351, Korea (e-mail: )
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Ross J, Bowden MR, Yu C, Diaz-Thomas A. Transition of young adults with metabolic bone diseases to adult care. Front Endocrinol (Lausanne) 2023; 14:1137976. [PMID: 37008909 PMCID: PMC10064010 DOI: 10.3389/fendo.2023.1137976] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Accepted: 03/06/2023] [Indexed: 03/19/2023] Open
Abstract
As more accurate diagnostic tools and targeted therapies become increasingly available for pediatric metabolic bone diseases, affected children have a better prognosis and significantly longer lifespan. With this potential for fulfilling lives as adults comes the need for dedicated transition and intentional care of these patients as adults. Much work has gone into improving the transitions of medically fragile children into adulthood, encompassing endocrinologic conditions like type 1 diabetes mellitus and congenital adrenal hyperplasia. However, there are gaps in the literature regarding similar guidance concerning metabolic bone conditions. This article intends to provide a brief review of research and guidelines for transitions of care more generally, followed by a more detailed treatment of bone disorders specifically. Considerations for such transitions include final adult height, fertility, fetal risk, heritability, and access to appropriately identified specialists. A nutrient-dense diet, optimal mobility, and adequate vitamin D stores are protective factors for these conditions. Primary bone disorders include hypophosphatasia, X-linked hypophosphatemic rickets, and osteogenesis imperfecta. Metabolic bone disease can also develop secondarily as a sequela of such diverse exposures as hypogonadism, a history of eating disorder, and cancer treatment. This article synthesizes research by experts of these specific disorders to describe what is known in this field of transition medicine for metabolic bone diseases as well as unanswered questions. The long-term objective is to develop and implement strategies for successful transitions for all patients affected by these various conditions.
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Affiliation(s)
- Jordan Ross
- Division of Pediatric Endocrinology, University of Tennessee Health Science Center, Memphis, TN, United States
- *Correspondence: Jordan Ross,
| | - Michelle R. Bowden
- Division of General Pediatrics, University of Tennessee Health Science Center, Memphis, TN, United States
- Le Bonheur Children’s Hospital, Memphis, TN, United States
| | - Christine Yu
- Endocrinology Division, St. Jude Children’s Research Hospital, Memphis, TN, United States
| | - Alicia Diaz-Thomas
- Division of Pediatric Endocrinology, University of Tennessee Health Science Center, Memphis, TN, United States
- Le Bonheur Children’s Hospital, Memphis, TN, United States
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Osteomalacia Is Not a Single Disease. Int J Mol Sci 2022; 23:ijms232314896. [PMID: 36499221 PMCID: PMC9740398 DOI: 10.3390/ijms232314896] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2022] [Revised: 11/18/2022] [Accepted: 11/23/2022] [Indexed: 11/29/2022] Open
Abstract
Among bone-material qualities, mineralization is pivotal in conferring stiffness and toughness to the bone. Osteomalacia, a disease ensuing from inadequate mineralization of the skeleton, is caused by different processes leading to decreased available mineral (calcium and/or phosphate) or enzymatic alterations. Vitamin D deficiency, which remains the major cause of altered mineralization leading to inadequate intestinal calcium and phosphate absorption, may be also associated with other conditions primarily responsible for abnormal mineralization. Given the reality of widespread vitamin D inadequacy, a full biochemical assessment of mineral metabolism is always necessary to rule out or confirm other conditions. Both too-high or too-low serum alkaline phosphatase (ALP) levels are important for diagnosis. Osteomalacic syndrome is reversible, at least in part, by specific treatment. Osteomalacia and bone mineralization themselves constitute largely unexplored fields of research. The true prevalence of the different forms of osteomalacia and the recovery after proper therapy have yet to be determined in the real world. Although non-invasive techniques to assess bone mineralization are not available in clinical practice, the systematic assessment of bone quality could help in refining the diagnosis and guiding the treatment. This review summarizes what is known of osteomalacia recent therapeutic developments and highlights the future issues of research in this field.
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Koh AJ, Nam HK, Michalski MN, Do J, McCauley LK, Hatch NE. Anabolic actions of parathyroid hormone in a hypophosphatasia mouse model. Osteoporos Int 2022; 33:2423-2433. [PMID: 35871207 PMCID: PMC9568459 DOI: 10.1007/s00198-022-06496-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Accepted: 07/07/2022] [Indexed: 11/17/2022]
Abstract
UNLABELLED Hypophosphatasia, the rare heritable disorder caused by TNAP enzyme mutations, presents wide-ranging severity of bone hypomineralization and skeletal abnormalities. Intermittent PTH (1-34) increased long bone volume in Alpl-/- mice but did not alter the skull phenotype. PTH may have therapeutic value for adults with TNAP deficiency-associated osteoporosis. INTRODUCTION Hypophosphatasia is the rare heritable disorder caused by mutations in the tissue non-specific alkaline phosphatase (TNAP) enzyme leading to TNAP deficiency. Individuals with hypophosphatasia commonly present with bone hypomineralization and skeletal abnormalities. The purpose of this study was to determine the impact of intermittent PTH on the skeletal phenotype of TNAP-deficient Alpl-/- mice. METHODS Alpl-/- and Alpl+/+ (wild-type; WT) littermate mice were administered PTH (1-34) (50 µg/kg) or vehicle control from days 4 to 12 and skeletal analyses were performed including gross measurements, micro-CT, histomorphometry, and serum biochemistry. RESULTS Alpl-/- mice were smaller with shorter tibial length and skull length compared to WT mice. Tibial BV/TV was reduced in Alpl-/- mice and daily PTH (1-34) injections significantly increased BV/TV and BMD but not TMD in both WT and Alpl-/- tibiae. Trabecular spacing was not different between genotypes and was decreased by PTH in both genotypes. Serum P1NP was unchanged while TRAcP5b was significantly lower in Alpl-/- vs. WT mice, with no PTH effect, and no differences in osteoclast numbers. Skull height and width were increased in Alpl-/- vs. WT mice, and PTH increased skull width in WT but not Alpl-/- mice. Frontal skull bones in Alpl-/- mice had decreased BV/TV, BMD, and calvarial thickness vs. WT with no significant PTH effects. Lengths of cranial base bones (basioccipital, basisphenoid, presphenoid) and lengths of synchondroses (growth plates) between the cranial base bones, plus bone of the basioccipitus, were assessed. All parameters were reduced (except lengths of synchondroses, which were increased) in Alpl-/- vs. WT mice with no PTH effect. CONCLUSION PTH increased long bone volume in the Alpl-/- mice but did not alter the skull phenotype. These data suggest that PTH can have long bone anabolic activity in the absence of TNAP, and that PTH may have therapeutic value for individuals with hypophosphatasia-associated osteoporosis.
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Affiliation(s)
- Amy J Koh
- Department of Periodontology and Oral Medicine, School of Dentistry, University of Michigan, Ann Arbor, MI, USA
| | - Hwa Kyung Nam
- Department of Orthodontics and Pediatric Dentistry, School of Dentistry, University of Michigan, Ann Arbor, MI, USA
| | - Megan N Michalski
- Department of Cell Biology, Van Andel Institute, Grand Rapids, MI, USA
| | - Justin Do
- Department of Periodontology and Oral Medicine, School of Dentistry, University of Michigan, Ann Arbor, MI, USA
| | - Laurie K McCauley
- Department of Periodontology and Oral Medicine, School of Dentistry, University of Michigan, Ann Arbor, MI, USA.
- Department of Pathology, School of Medicine, University of Michigan, Ann Arbor, MI, USA.
| | - Nan E Hatch
- Department of Orthodontics and Pediatric Dentistry, School of Dentistry, University of Michigan, Ann Arbor, MI, USA.
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Okawa R, Nakano K. Dental manifestation and management of hypophosphatasia. JAPANESE DENTAL SCIENCE REVIEW 2022; 58:208-216. [PMID: 35814738 PMCID: PMC9260292 DOI: 10.1016/j.jdsr.2022.06.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 06/22/2022] [Accepted: 06/26/2022] [Indexed: 11/24/2022] Open
Abstract
Hypophosphatasia is an inherited metabolic disorder characterized by defective mineralization of bones and teeth with a wide variety of manifestations, ranging from stillbirth to dental symptoms alone. Recently, the prognosis of severe hypophosphatasia patients has been greatly improved by the introduction of enzyme replacement therapy. The typical dental manifestation is early exfoliation of primary teeth due to disturbed cementum formation, so dentures are recommended to ensure that important oral functions are acquired. Some studies have shown that enzyme replacement therapy improves dental mineralization, resulting in the stabilization of periodontal tissues and better growth of tooth roots. A nationwide Japanese survey revealed the common genetic and dental manifestations of patients with mild hypophosphatasia, which markedly differ from those of the severe forms. There may be many undiagnosed mild patients, so dentists should contribute to the early diagnosis by screening possible cases based on the typical finding of early exfoliation of primary teeth. Early diagnosis is important for patients to receive early intervention in both medical and dental fields. The establishment of fundamental dental therapy to solve the dental problems is still underway and is eagerly anticipated.
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Roumpou A, Yavropoulou MP, Chronopoulos E, Kassi E. Novel Therapeutic Agents for Rare Diseases of Calcium and Phosphate Metabolism. Horm Metab Res 2022; 54:645-657. [PMID: 36049757 DOI: 10.1055/a-1917-0519] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
The last decade has been revolutionary regarding the management of rare bone diseases caused by impaired calcium and phosphate metabolism. Elucidation of the underlying genetic basis and pathophysiologic alterations has been the determinant factor for the development of new, disease-specific treatment agents. The phosphaturic hormone Fibroblast Growth Factor 23 (FGF23) possesses a critical role in the pathogenesis of various hypophosphatemic disorders. Among them, the genetic disorder of X-linked hypophosphatemia and the acquired syndrome of tumor-induced osteomalacia, although very rare, have attracted the scientific community's attention towards designing an FGF23-inhibitor as a potential specific therapy. The monoclonal antibody burosumab was approved for the treatment of children and adult patients with X-linked hypophosphatemia and recently for tumor-induced osteomalacia patients, demonstrating benefits regarding their symptoms, biochemical profile and bone mineralization status. Asfotase alfa is a hydroxyapatite-targeted recombinant alkaline phosphatase, an enzymatic replacement therapy, substituting the defective activity of tissue non-specific alkaline phosphatase, in patients suffering from hypophosphatasia. Promising data regarding its favorable effect on survival rate, bone quality, fracture healing, muscle strength, mobility, respiratory function, and general quality of life have led to the approval of the drug for the treatment of childhood-onset hypophosphatasia. Given the high costs of treatment for both agents and their limited clinical use until now, more data are needed to define patients' characteristics that make them ideal candidates for therapy. Long-term safety issues also need to be clarified.
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Affiliation(s)
- Afroditi Roumpou
- Division of Endocrinology, Metabolism and Diabetes, First Department of Pediatrics, "Aghia Sofia" Children's Hospital, National and Kapodistrian University of Athens School of Medicine, Athens, Greece
- Laboratory for Research of the Musculoskeletal System, National and Kapodistrian University of Athens School of Medicine, Athens, Greece
| | - Maria P Yavropoulou
- Centre of Expertise for Rare Endocrine Diseases, C.E.R.E.D. Disorders of Calcium & Phosphate Metabolism, First Department of Propaedeutic and Internal Medicine, Laiko Hospital, National and Kapodistrian University of Athens School of Medicine, Athens, Greece
| | - Efstathios Chronopoulos
- Laboratory for Research of the Musculoskeletal System, National and Kapodistrian University of Athens School of Medicine, Athens, Greece
| | - Eva Kassi
- Laboratory for Research of the Musculoskeletal System, National and Kapodistrian University of Athens School of Medicine, Athens, Greece
- Centre of Expertise for Rare Endocrine Diseases, C.E.R.E.D. Disorders of Calcium & Phosphate Metabolism, First Department of Propaedeutic and Internal Medicine, Laiko Hospital, National and Kapodistrian University of Athens School of Medicine, Athens, Greece
- Department of Biological Chemistry, National and Kapodistrian University of Athens, Athens, Greece
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Collins MT, Marcucci G, Anders HJ, Beltrami G, Cauley JA, Ebeling PR, Kumar R, Linglart A, Sangiorgi L, Towler DA, Weston R, Whyte MP, Brandi ML, Clarke B, Thakker RV. Skeletal and extraskeletal disorders of biomineralization. Nat Rev Endocrinol 2022; 18:473-489. [PMID: 35578027 DOI: 10.1038/s41574-022-00682-7] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 04/13/2022] [Indexed: 12/15/2022]
Abstract
The physiological process of biomineralization is complex and deviation from it leads to a variety of diseases. Progress in the past 10 years has enhanced understanding of the genetic, molecular and cellular pathophysiology underlying these disorders; sometimes, this knowledge has both facilitated restoration of health and clarified the very nature of biomineralization as it occurs in humans. In this Review, we consider the principal regulators of mineralization and crystallization, and how dysregulation of these processes can lead to human disease. The knowledge acquired to date and gaps still to be filled are highlighted. The disorders of mineralization discussed comprise a broad spectrum of conditions that encompass bone disorders associated with alterations of mineral quantity and quality, as well as disorders of extraskeletal mineralization (hyperphosphataemic familial tumoural calcinosis). Included are disorders of alkaline phosphatase (hypophosphatasia) and phosphate homeostasis (X-linked hypophosphataemic rickets, fluorosis, rickets and osteomalacia). Furthermore, crystallopathies are covered as well as arterial and renal calcification. This Review discusses the current knowledge of biomineralization derived from basic and clinical research and points to future studies that will lead to new therapeutic approaches for biomineralization disorders.
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Affiliation(s)
- Michael T Collins
- Skeletal Disorders and Mineral Homeostasis Section, National Institute of Dental and Craniofacial Research, NIH, Bethesda, MD, USA.
| | - Gemma Marcucci
- Bone Metabolic Diseases Unit, Department of Biomedical, Experimental and Clinical Sciences, University of Florence, Florence, Italy
| | - Hans-Joachim Anders
- Department of Medicine IV, Hospital of the University of Munich, Ludwig-Maximilians University, Munich, Germany
| | - Giovanni Beltrami
- Department Paediatric Orthopedic Oncology, Careggi and Meyer Children Hospital, Florence, Italy
| | - Jane A Cauley
- Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA, USA
| | - Peter R Ebeling
- Department of Medicine, School of Clinical Sciences, Monash University, Melbourne, Australia
| | - Rajiv Kumar
- Departments of Medicine, Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN, USA
| | - Agnès Linglart
- APHP, Endocrinologie et diabète de l'enfant, Paris, France
| | - Luca Sangiorgi
- Medical Genetics and Skeletal Rare Diseases, IRCCS Istituto Ortopedico Rizzoli, Bologna, Italy
| | - Dwight A Towler
- University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Ria Weston
- Cardiovascular Research Group, Manchester Metropolitan University, Manchester, UK
| | - Michael P Whyte
- Center for Metabolic Bone Disease and Molecular Research, Shriners Hospitals for Children-St Louis, St Louis, MO, USA
- Division of Bone and Mineral Diseases, Department of Internal Medicine, Washington University School of Medicine, St Louis, MO, USA
| | | | - Bart Clarke
- Mayo Clinic Division of Endocrinology, Diabetes, Metabolism, and Nutrition, Rochester, MN, USA
| | - Rajesh V Thakker
- Academic Endocrine Unit, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
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Lin Z, Zhao D, Lin J, Ni A, Lin J. Statistical methods of indirect comparison with real-world data for survival endpoint under non-proportional hazards. J Biopharm Stat 2022; 32:582-599. [PMID: 35675418 DOI: 10.1080/10543406.2022.2080696] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
In clinical studies that utilize real-world data, time-to-event outcomes are often germane to scientific questions of interest. Two main obstacles are the presence of non-proportional hazards and confounding bias. Existing methods that could adjust for NPH or confounding bias, but no previous work delineated the complexity of simultaneous adjustments for both. In this paper, a propensity score stratified MaxCombo and weighted Cox model is proposed. This model can adjust for confounding bias and NPH and can be pre-specified when NPH pattern is unknown in advance. The method has robust performance as demonstrated in simulation studies and in a case study.
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Affiliation(s)
- Zihan Lin
- Division of Biostatistics, College of Public Health, the Ohio State University, Columbus, Ohio, USA
| | - Dan Zhao
- Biometrics Department, Servier Pharmaceuticals, Boston, Massachusetts, USA
| | - Junjing Lin
- Statistical and Quantitative Sciences, Takeda Pharmaceuticals, Cambridge, Massachusetts, USA
| | - Ai Ni
- Division of Biostatistics, College of Public Health, the Ohio State University, Columbus, Ohio, USA
| | - Jianchang Lin
- Statistical and Quantitative Sciences, Takeda Pharmaceuticals, Cambridge, Massachusetts, USA
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Kato H, Hidaka N, Koga M, Kinoshita Y, Makita N, Nangaku M, Ito N. Radiological evaluation of pseudofracture after the administration of asfotase alfa in an adult with benign prenatal hypophosphatasia: A case report. Bone Rep 2022; 16:101163. [PMID: 35024386 PMCID: PMC8728307 DOI: 10.1016/j.bonr.2021.101163] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Revised: 12/24/2021] [Accepted: 12/27/2021] [Indexed: 11/28/2022] Open
Abstract
Hypophosphatasia (HPP) is a congenital disorder with decreased activity of tissue-nonspecific alkaline phosphatase. Asfotase alfa is the only treatment approved for HPP and improves the impairment of bone mineralization. Although several previous studies have reported the efficacy of asfotase alfa to treat fractures and pseudofractures in patients with HPP, there are only a few reports with a detailed description of the healing process. In this case report, we present an 18-year-old female patient with benign prenatal HPP who received asfotase alfa to treat her pseudofracture. At the age of 17, a pseudofracture developed in her left tibia after repetitive gymnastic exercise for months. Following observation over a year, she was referred to our department. X-ray images indicated a narrow radiolucent band in the mid-diaphysis of her left tibia, and bone scintigraphy showed nuclide accumulation in the same region. Replacement therapy with asfotase alfa was started, resulting in pain relief in two months, and the disappearance of nuclide accumulation on bone scintigraphy and union of the pseudofracture on X-ray after two years. This is the first case report describing the detailed pseudofracture healing process in a patient with benign prenatal HPP initiating asfotase alfa.
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Affiliation(s)
- Hajime Kato
- Division of Nephrology and Endocrinology, The University of Tokyo Hospital, Japan
| | - Naoko Hidaka
- Division of Nephrology and Endocrinology, The University of Tokyo Hospital, Japan
| | - Minae Koga
- Division of Nephrology and Endocrinology, The University of Tokyo Hospital, Japan
| | - Yuka Kinoshita
- Division of Nephrology and Endocrinology, The University of Tokyo Hospital, Japan
| | - Noriko Makita
- Division of Nephrology and Endocrinology, The University of Tokyo Hospital, Japan
| | - Masaomi Nangaku
- Division of Nephrology and Endocrinology, The University of Tokyo Hospital, Japan
| | - Nobuaki Ito
- Division of Nephrology and Endocrinology, The University of Tokyo Hospital, Japan
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Imaging patterns in pediatric hypophosphatasia. Pediatr Radiol 2022; 52:998-1006. [PMID: 34854966 DOI: 10.1007/s00247-021-05232-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Revised: 08/23/2021] [Accepted: 10/20/2021] [Indexed: 10/19/2022]
Abstract
Hypophosphatasia is a rare genetic disorder of calcium and phosphate metabolism due to ALPL gene mutations, which leads to abnormal mineralization of the bones and teeth. Hypophosphatasia is characterized by low serum alkaline phosphatase activity and a number of clinical signs, including failure to thrive, bone pain and dental issues. The diagnosis is suspected based on clinical, laboratory and imaging findings and confirmed by genetic testing. Diagnosis in children is often delayed due to a lack of disease awareness, despite specific imaging findings that are a cornerstone of the diagnosis. The recent approval of enzyme replacement therapy (bone-targeted recombinant tissue nonspecific alkaline phosphatase) has given imaging an important role in monitoring treatment efficacy. The aim of this pictorial essay is to review the imaging features of hypophosphatasia at diagnosis and during follow-up, including whole-body magnetic resonance imaging patterns.
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Nam HK, Emmanouil E, Hatch NE. Deletion of the Pyrophosphate Generating Enzyme ENPP1 Rescues Craniofacial Abnormalities in the TNAP−/− Mouse Model of Hypophosphatasia and Reveals FGF23 as a Marker of Phenotype Severity. FRONTIERS IN DENTAL MEDICINE 2022; 3. [PMID: 35909501 PMCID: PMC9336114 DOI: 10.3389/fdmed.2022.846962] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Hypophosphatasia is a rare heritable metabolic disorder caused by deficient Tissue Non-specific Alkaline Phosphatase (TNAP) enzyme activity. A principal function of TNAP is to hydrolyze the tissue mineralization inhibitor pyrophosphate. ENPP1 (Ectonucleotide Pyrophosphatase/Phosphodiesterase 1) is a primary enzymatic generator of pyrophosphate and prior results showed that elimination of ENPP1 rescued bone hypomineralization of skull, vertebral and long bones to different extents in TNAP null mice. Current TNAP enzyme replacement therapy alleviates skeletal, motor and cognitive defects but does not eliminate craniosynostosis in pediatric hypophosphatasia patients. To further understand mechanisms underlying craniosynostosis development in hypophosphatasia, here we sought to determine if craniofacial abnormalities including craniosynostosis and skull shape defects would be alleviated in TNAP null mice by genetic ablation of ENPP1. Results show that homozygous deletion of ENPP1 significantly diminishes the incidence of craniosynostosis and that skull shape abnormalities are rescued by hemi- or homozygous deletion of ENPP1 in TNAP null mice. Skull and long bone hypomineralization were also alleviated in TNAP−/−/ENPP1−/− compared to TNAP−/−/ENPP1+/+ mice, though loss of ENPP1 in combination with TNAP had different effects than loss of only TNAP on long bone trabeculae. Investigation of a relatively large cohort of mice revealed that the skeletal phenotypes of TNAP null mice were markedly variable. Because FGF23 circulating levels are known to be increased in ENPP1 null mice and because FGF23 influences bone, we measured serum intact FGF23 levels in the TNAP null mice and found that a subset of TNAP−/−/ENPP1+/+ mice exhibited markedly high serum FGF23. Serum FGF23 levels also correlated to mouse body measurements, the incidence of craniosynostosis, skull shape abnormalities and skull bone density and volume fraction. Together, our results demonstrate that balanced expression of TNAP and ENPP1 enzymes are essential for microstructure and mineralization of both skull and long bones, and for preventing craniosynostosis. The results also show that FGF23 rises in the TNAP−/− model of murine lethal hypophosphatasia. Future studies are required to determine if the rise in FGF23 is a cause, consequence, or marker of disease phenotype severity.
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Krishnan N, Dunbar N. Management of perinatal HPP during critical illness/ECMO. J Pediatr Endocrinol Metab 2022; 35:115-119. [PMID: 34582635 DOI: 10.1515/jpem-2021-0187] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Accepted: 09/06/2021] [Indexed: 11/15/2022]
Abstract
OBJECTIVES With the advent of asfotase alfa, the enzyme replacement therapy (ERT) approved for hypophosphatasia (HPP), health care providers need to navigate management of ERT during critical illness. CASE PRESENTATION We present the case of a young girl, treated with ERT for severe perinatal HPP, who had cardiorespiratory arrest in the setting of influenza A. Her life-saving treatment involving extra corporeal membrane oxygenation (ECMO) required a two-week interruption of ERT leading to persistent hypercalcemia and hyperphosphatemia. A three year old female presented with respiratory distress and blood tinged secretions. She was influenza A positive with bilateral opacities on chest X-ray (CXR). Worsening respiratory distress and bradycardic arrest required intubation, CPR and venoarterial ECMO cannulation. She remained on ECMO for 10 days with anticoagulation restrictions requiring her thrice-weekly subcutaneous ERT to be held. Hypercalcemia (12.3 mg/dL) and hyperphosphatemia (7.6 mg/dL) developed two weeks after restarting ERT and resolved six weeks later. CONCLUSIONS We highlight that the obligatory cessation of ERT while on ECMO led to the loss of functional TNSALP with a profound decrease in bone mineralization leading to excess circulating calcium and phosphorus. In cases where it is necessary to interrupt ERT, we advise close monitoring of calcium and phosphorous levels.
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Affiliation(s)
- Neetu Krishnan
- Department of Pediatric Endocrinology, University of Connecticut, Farmington, CT, USA
| | - Nancy Dunbar
- Department of Pediatric Endocrinology, Connecticut Children's, Farmington, CT, USA
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Verminderte Mineralisation des Knochens: Rachitis und Osteomalazie. Monatsschr Kinderheilkd 2022. [DOI: 10.1007/s00112-021-01392-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
ZusammenfassungDie Mineralisation der Wachstumsfuge und des Knochens benötigt suffiziente Mengen an Kalzium und Phosphat, um ein adäquates Körperwachstum und eine adäquate Knochenstärke zu gewährleisten. Bei Mangelzuständen nehmen Härte und Stärke des Knochens ab (Osteomalazie), mit typischen Veränderungen an der Wachstumsfuge (Rachitis). Die vermeidbaren Komplikationen einer erworbenen Rachitis können lebensbedrohlich sein und sind auch deshalb ein global wichtiges Public-Health-Thema. Typische klinische Zeichen, Laborparameter und radiologische Veränderungen sollten zur unverzüglichen Diagnose führen. Erbliche und erworbene Formen der Rachitis wie X‑chromosomale Hypophosphatämie oder Hypophosphatasie werden, wie oftmals bei seltenen Erkrankungen, spät diagnostiziert. Diagnose, Therapie und Management von Rachitiden sollten durch tertiäre kinderosteologische Spezialisten erfolgen, die in internationalen „Rare-diseases“-Netzwerken arbeiten und in enger Kooperation mit Selbsthilfegruppen stehen.
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Evaluation of alveolar bone hypomineralization in pediatric hypophosphatasia using orthopantomography. Sci Rep 2022; 12:1211. [PMID: 35075203 PMCID: PMC8786966 DOI: 10.1038/s41598-022-05171-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Accepted: 01/07/2022] [Indexed: 12/15/2022] Open
Abstract
Hypophosphatasia (HPP) is a metabolic disease characterized by impaired bone mineralization and early exfoliation of primary teeth. This study was performed to develop a method for quantitatively evaluating alveolar bone hypomineralization using orthopantomographic images. Alveolar bone density was defined according to the pixel values and corrected by brightness shown by an indicator applied to the orthopantomographic device. Images of 200 healthy subjects (aged 2-15 years) were classified into five age groups. The corrected pixel values were significantly lower in the younger group than in those aged 14-15 years (2-4, 5-7, and 8-10 years versus 14-15 years: P < 0.0001, 11-13 years versus 14-15 years: P < 0.01). Orthopantomographic images of 17 patients with HPP were evaluated. The corrected pixel values of three-fourths of the patients with odonto type HPP were lower than the mean values of the healthy group. One-third of patients treated with enzyme replacement therapy showed higher corrected pixel values than the healthy group. Our results suggest that odonto type HPP without skeletal problems is occasionally accompanied by hypomineralization of alveolar bone and that alveolar bone hypomineralization in patients with severe HPP is possibly improved by enzyme replacement therapy.
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Whyte MP, Zhang F, Wenkert D, Mack KE, Bijanki VN, Ericson KL, Coburn SP. Hypophosphatasia: Vitamin B 6 status of affected children and adults. Bone 2022; 154:116204. [PMID: 34547524 DOI: 10.1016/j.bone.2021.116204] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Revised: 09/09/2021] [Accepted: 09/14/2021] [Indexed: 12/20/2022]
Abstract
Hypophosphatasia (HPP) is the heritable dento-osseous disease caused by loss-of-function mutation(s) of the gene ALPL that encodes the tissue-nonspecific isoenzyme of alkaline phosphatase (TNSALP). TNSALP is a cell-surface homodimeric phosphomonoester phosphohydrolase expressed in healthy people especially in the skeleton, liver, kidneys, and developing teeth. In HPP, diminished TNSALP activity leads to extracellular accumulation of its natural substrates including inorganic pyrophosphate (PPi), an inhibitor of mineralization, and pyridoxal 5'-phosphate (PLP), the principal circulating form of vitamin B6 (B6). Autosomal dominant and autosomal recessive inheritance involving >450 usually missense defects scattered throughout ALPL largely explains the remarkably broad-ranging severity of this inborn-error-of-metabolism. In 1985 when we identified elevated plasma PLP as a biochemical hallmark of HPP, all 14 investigated affected children and adults had markedly increased PLP levels. However, pyridoxal (PL), the dephosphorylated form of PLP that enters cells to cofactor many enzymatic reactions, was not low but often inexplicably elevated. Levels of pyridoxic acid (PA), the B6 degradation product quantified to assess B6 sufficiency, were unremarkable. Canonical signs or symptoms of B6 deficiency or toxicity were absent. B6-dependent seizures in infants with life-threatening HPP were later explained by their profound deficiency of TNSALP activity blocking PLP dephosphorylation to PL and diminishing gamma-aminobutyric acid synthesis in the brain. Now, there is speculation that altered B6 metabolism causes further clinical complications in HPP. Herein, we assessed the plasma PL and PA levels accompanying previously reported elevated plasma PLP concentrations in 150 children and adolescents with HPP. Their mean (SD) plasma PL level was nearly double the mean for our healthy pediatric controls: 66.7 (59.0) nM versus 37.1 (22.2) nM (P < 0.0001), respectively. Their PA levels were broader than our pediatric control range, but their mean value was normal; 40.2 (25.1) nM versus 39.3 (9.9) nM (P = 0.7793), respectively. In contrast, adults with HPP often had plasma PL and PA levels suggestive of dietary B6 insufficiency. We discuss why the B6 levels of our pediatric patients with HPP would not cause B6 toxicity or deficiency, whereas in affected adults dietary B6 insufficiency can develop.
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Affiliation(s)
- Michael P Whyte
- Center for Metabolic Bone Disease and Molecular Research, Shriners Hospitals for Children - St. Louis, St. Louis, MO 63110, USA; Division of Bone and Mineral Diseases, Department of Internal Medicine, Washington University School of Medicine at Barnes-Jewish Hospital, St. Louis, MO 63110, USA.
| | - Fan Zhang
- Center for Metabolic Bone Disease and Molecular Research, Shriners Hospitals for Children - St. Louis, St. Louis, MO 63110, USA.
| | - Deborah Wenkert
- Center for Metabolic Bone Disease and Molecular Research, Shriners Hospitals for Children - St. Louis, St. Louis, MO 63110, USA.
| | - Karen E Mack
- Center for Metabolic Bone Disease and Molecular Research, Shriners Hospitals for Children - St. Louis, St. Louis, MO 63110, USA.
| | - Vinieth N Bijanki
- Center for Metabolic Bone Disease and Molecular Research, Shriners Hospitals for Children - St. Louis, St. Louis, MO 63110, USA.
| | - Karen L Ericson
- Department of Chemistry, Purdue University Fort Wayne, Fort Wayne, IN 46805, USA.
| | - Stephen P Coburn
- Department of Chemistry, Purdue University Fort Wayne, Fort Wayne, IN 46805, USA.
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50
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Thrailkill KM, Kalaitzoglou E, Fowlkes JL. Emerging therapies for the treatment of rare pediatric bone disorders. Front Pediatr 2022; 10:1012816. [PMID: 36304528 PMCID: PMC9592743 DOI: 10.3389/fped.2022.1012816] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Accepted: 09/09/2022] [Indexed: 11/24/2022] Open
Abstract
In recent years, new therapies for the treatment of rare pediatric bone disorders have emerged, guided by an increasing understanding of the genetic and molecular etiology of these diseases. Herein, we review three such disorders, impacted by debilitating deficits in bone mineralization or cartilage ossification, as well as the novel disease-modifying drugs that are now available to treat these conditions. Specifically, we discuss asfotase alfa, burosumab-twza, and vosoritide, for the treatment of hypophosphatasia, X-linked hypophosphatemia and achondroplasia, respectively. For each skeletal disorder, an overview of the clinical phenotype and natural history of disease is provided, along with a discussion of the clinical pharmacology, mechanism of action and FDA indication for the relevant medication. In each case, a brief review of clinical trial data supporting drug development for each medication is provided. Additionally, guidance as to drug dosing and long-term monitoring of adverse events and pediatric efficacy is presented, to aid the clinician seeking to utilize these novel therapies in their practice, or to become familiar with the healthcare expectations for children receiving these medications through specialized multidisciplinary clinics. The availability of these targeted therapies now significantly augments treatment options for conditions in which past therapy has relied upon less specific, symptomatic medical and orthopedic care.
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Affiliation(s)
- Kathryn M Thrailkill
- Department of Pediatrics, University of Kentucky Barnstable Brown Diabetes Center, University of Kentucky College of Medicine, Lexington, KY, United States
| | - Evangelia Kalaitzoglou
- Department of Pediatrics, University of Kentucky Barnstable Brown Diabetes Center, University of Kentucky College of Medicine, Lexington, KY, United States
| | - John L Fowlkes
- Department of Pediatrics, University of Kentucky Barnstable Brown Diabetes Center, University of Kentucky College of Medicine, Lexington, KY, United States
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