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Yue H, Cao H, Zhi Y, Song G, Cheng J, He M. Molecular study of patients with odontohypophosphatasia resulting from missense mutation in ALPL. Oral Dis 2024. [PMID: 38591765 DOI: 10.1111/odi.14955] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Revised: 03/25/2024] [Accepted: 03/27/2024] [Indexed: 04/10/2024]
Affiliation(s)
- Haitang Yue
- State Key Laboratory of Oral & Maxillofacial Reconstruction and Regeneration, Key Laboratory of Oral Biomedicine Ministry of Education, Hubei Key Laboratory of Stomatology, School & Hospital of Stomatology, Wuhan University, Wuhan, China
| | - Haiyan Cao
- State Key Laboratory of Oral & Maxillofacial Reconstruction and Regeneration, Key Laboratory of Oral Biomedicine Ministry of Education, Hubei Key Laboratory of Stomatology, School & Hospital of Stomatology, Wuhan University, Wuhan, China
| | - Yusheng Zhi
- State Key Laboratory of Oral & Maxillofacial Reconstruction and Regeneration, Key Laboratory of Oral Biomedicine Ministry of Education, Hubei Key Laboratory of Stomatology, School & Hospital of Stomatology, Wuhan University, Wuhan, China
| | - Guangtai Song
- Department of Paediatric Dentistry, School and Hospital of Stomatology, Wuhan University, Wuhan, China
| | - Jing Cheng
- Department of Paediatric Dentistry, School and Hospital of Stomatology, Wuhan University, Wuhan, China
| | - Miao He
- State Key Laboratory of Oral & Maxillofacial Reconstruction and Regeneration, Key Laboratory of Oral Biomedicine Ministry of Education, Hubei Key Laboratory of Stomatology, School & Hospital of Stomatology, Wuhan University, Wuhan, China
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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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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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Kishnani PS, Martos-Moreno GÁ, Linglart A, Petryk A, Messali A, Fang S, Rockman-Greenberg C, Ozono K, Högler W, Seefried L, Dahir KM. Effectiveness of asfotase alfa for treatment of adults with hypophosphatasia: results from a global registry. Orphanet J Rare Dis 2024; 19:109. [PMID: 38459585 PMCID: PMC10921796 DOI: 10.1186/s13023-024-03048-6] [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: 09/12/2023] [Accepted: 01/19/2024] [Indexed: 03/10/2024] Open
Abstract
BACKGROUND Hypophosphatasia (HPP) is a rare inherited disease caused by deficient activity of tissue-nonspecific alkaline phosphatase. Many adults with HPP have a high burden of disease, experiencing chronic pain, fatigue, limited mobility, and dental issues, contributing to decreased health-related quality of life (HRQoL). HPP may be treated with the enzyme replacement therapy asfotase alfa though real-world data in adults are limited. This analysis was conducted to assess the clinical effectiveness of asfotase alfa among adults in the Global HPP Registry. METHODS The Global HPP Registry is an observational, prospective, multinational study. Adults ≥ 18 years of age were included in this analysis if they had serum alkaline phosphatase (ALP) activity below the age- and sex-adjusted reference ranges, and/or ALPL variant(s), and received asfotase alfa for ≥ 6 months. Mobility was assessed with the 6-Minute Walk Test (6MWT), and patient-reported outcomes tools were used to assess pain (Brief Pain Inventory-Short Form), quality of life (36-item Short Form Health Survey, version 2 [SF-36v2]), and disability (Health Assessment Questionnaire-Disability Index) at multiple time points from baseline through Month 36. Data were collected as per usual standard of care; patients may not have contributed data at all time points. RESULTS A total of 190 patients met the inclusion criteria. For patients with ≥ 1 follow-up measurement, the mean distance achieved on 6MWT increased from 404 m (range 60-632 m) at baseline (n = 31) to 484 m at Month 12 (range 240-739 m; n = 18) and remained above baseline through Month 36 (n = 7). Improvements in mean self-reported pain severity scores ranged from - 0.72 (95% CI: - 1.23, - 0.21; n = 38) to - 1.13 (95% CI: - 1.76, - 0.51; n = 26) and were observed at all time points. Improvements in the Physical Component Summary score of SF-36v2 were achieved by Month 6 and sustained throughout follow-up. There was a trend toward improvement in the Mental Component Summary score of SF-36v2 at most time points, with considerable fluctuations from Months 12 (n = 28) through 36 (n = 21). The most frequent adverse events were injection site reactions. CONCLUSIONS Adults with HPP who received asfotase alfa for ≥ 6 months experienced improvements in mobility, physical function, and HRQoL, which were maintained over 3 years of follow-up. REGISTRATION NCT02306720; EUPAS13514.
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Affiliation(s)
- Priya S Kishnani
- Department of Pediatrics, Duke University Medical Center, 2351 Erwin Road, Durham, NC, 27710, USA.
| | - Gabriel Ángel Martos-Moreno
- Hospital Infantil Universitario Niño Jesús, IIS La Princesa, Universidad Autónoma de Madrid, CIBERobn, ISCIII, Madrid, Spain
| | - Agnès Linglart
- Paris-Saclay University, AP-HP and INSERM, Paris, France
| | - Anna Petryk
- Alexion, AstraZeneca Rare Disease, Boston, MA, USA
| | | | - Shona Fang
- Alexion, AstraZeneca Rare Disease, Boston, MA, USA
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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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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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Farman MR, Rehder C, Malli T, Rockman-Greenberg C, Dahir K, Martos-Moreno GÁ, Linglart A, Ozono K, Seefried L, Del Angel G, Webersinke G, Barbazza F, John LK, Delana Mudiyanselage SMA, Högler F, Nading EB, Huggins E, Rush ET, El-Gazzar A, Kishnani PS, Högler W. The Global ALPL gene variant classification project: Dedicated to deciphering variants. Bone 2024; 178:116947. [PMID: 37898381 DOI: 10.1016/j.bone.2023.116947] [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: 06/04/2023] [Revised: 10/15/2023] [Accepted: 10/17/2023] [Indexed: 10/30/2023]
Abstract
BACKGROUND Hypophosphatasia (HPP) is an inherited multisystem disorder predominantly affecting the mineralization of bones and teeth. HPP is caused by pathogenic variants in ALPL, which encodes tissue non-specific alkaline phosphatase (TNSALP). Variants of uncertain significance (VUS) cause diagnostic delay and uncertainty amongst patients and health care providers. RESULTS The ALPL gene variant database (https://alplmutationdatabase.jku.at/) is an open-access archive for interpretation of the clinical significance of variants reported in ALPL. The database contains coding and non-coding variants, including single nucleotide variants, insertions/deletions and structural variants affecting coding or non-coding sequences of ALPL. Each variant in the database is displayed with details explaining the corresponding pathogenicity, and all reported genotypes and phenotypes, including references. In 2021, the ALPL gene variant classification project was established to reclassify VUS and continuously assess and update genetic, phenotypic, and functional variant information in the database. For this purpose, the database provides a unique submission system for clinicians, geneticists, genetic counselors, and researchers to submit VUS within ALPL for classification. An international, multidisciplinary consortium of HPP experts has been established to reclassify the submitted VUS using a multi-step process adhering to the stringent ACMG/AMP variant classification guidelines. These steps include a clinical phenotype assessment, deep literature research including artificial intelligence technology, molecular genetic assessment, and in-vitro functional testing of variants in a co-transfection model to measure ALP residual activity. CONCLUSION This classification project and the ALPL gene variant database will serve the global medical community, widen the genotypic and phenotypic HPP spectrum by reporting and characterizing new ALPL variants based on ACMG/AMP criteria and thus facilitate improved genetic counseling and medical decision-making for affected patients and families. The project may also serve as a gold standard framework for multidisciplinary collaboration for variant interpretation in other rare diseases.
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Affiliation(s)
- Mariam R Farman
- Department of Paediatrics and Adolescent Medicine, Johannes Kepler University Linz, Linz, Austria
| | - Catherine Rehder
- Duke University Medical Center, Department of Pathology, Durham, USA
| | - Theodora Malli
- Laboratory for Molecular Genetic Diagnostics, Ordensklinikum Linz, Linz, Austria
| | - Cheryl Rockman-Greenberg
- Department of Pediatrics and Child Health Max Rady College of Medicine, Rady Faculty of Health Sciences, Winnipeg, Canada
| | - Kathryn Dahir
- Vanderbilt University Medical Center, Program for Metabolic Bone Disorders, Nashville, TN, USA
| | - Gabriel Ángel Martos-Moreno
- Departments of Pediatrics & Pediatric Endocrinology, Hospital Infantil Universitario Niño Jesús, Madrid, Spain
- Department of Pediatrics, Universidad Autónoma de Madrid, Madrid, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición, ISCIII, Madrid, Spain
| | - Agnès Linglart
- AP-HP, Paris Saclay University, INSERM, Bicêtre Paris Saclay hospital, Le Kremlin-Bicêtre, France
| | - Keiichi Ozono
- Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka, Japan
| | | | | | - Gerald Webersinke
- Laboratory for Molecular Genetic Diagnostics, Ordensklinikum Linz, Linz, Austria
| | - Francesca Barbazza
- Department of Paediatrics and Adolescent Medicine, Johannes Kepler University Linz, Linz, Austria
| | - Lisa K John
- Department of Paediatrics and Adolescent Medicine, Johannes Kepler University Linz, Linz, Austria
| | | | - Florian Högler
- Department of Paediatrics and Adolescent Medicine, Johannes Kepler University Linz, Linz, Austria
| | - Erica Burner Nading
- Duke University Medical Center, Division of Medical Genetics, Department of Pediatrics, Durham, USA
| | - Erin Huggins
- Duke University Medical Center, Division of Medical Genetics, Department of Pediatrics, Durham, USA
| | - Eric T Rush
- Division of Clinical Genetics, Children's Mercy Hospital Kansas City, Kansas City, MO, USA
- Department of Internal Medicine, University of Kansas School of Medicine, Kansas City, KS, USA
- Department of Pediatrics, University of Missouri – Kansas City School of Medicine, Kansas City, MO, USA
| | - Ahmed El-Gazzar
- Department of Paediatrics and Adolescent Medicine, Johannes Kepler University Linz, Linz, Austria
| | - Priya S Kishnani
- Duke University Medical Center, Division of Medical Genetics, Department of Pediatrics, Durham, USA
| | - Wolfgang Högler
- Department of Paediatrics and Adolescent Medicine, Johannes Kepler University Linz, Linz, Austria
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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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10
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Kim SM, Korkmaz F, Sims S, Ryu V, Yuen T, Zaidi M. Musculoskeletal and neurocognitive clinical significance of adult hypophosphatasia. Osteoporos Sarcopenia 2023; 9:115-120. [PMID: 38374822 PMCID: PMC10874721 DOI: 10.1016/j.afos.2023.12.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/07/2023] [Revised: 12/03/2023] [Accepted: 12/12/2023] [Indexed: 02/21/2024] Open
Abstract
Hypophosphatasia (HPP), also called Rathbun disease, is a rare genetic disorder that is caused by the loss-of-function mutation in the ALPL gene encoding tissue non-specific alkaline phosphatase. Doctor Rathbun first described the case of a 3-week-old infant who presented with severe osteopenia, rickets, and multiple radiographic fractures, and died shortly after of epileptic seizure and respiratory distress. The term "hypophosphatasia" was coined as the patients' alkaline phosphatase levels were significantly low. Since then, our understanding of HPP has evolved, and now we appreciate causative genetic mutation and the broad spectrum of clinical presentation depending on the age of onset, severity, and skeletal involvement: perinatal, infantile, childhood, adult and odontohypophosphatasia. The new development of enzyme replacement with asfostase alfa has saved the lives of severe form of hypophosphatasia. However, it is still unclear and remains challenging how to manage adult HPP that often presents with mild and non-specific symptoms such as muscle pain, joint stiffness, fatigue, anxiety, or low bone mass, which are common in the general population and not necessarily attributed to HPP. In this review, we will present 3 unique cases of adult HPP and discuss the pathophysiology, clinical presentation particularly neuromuscular and neurocognitive symptoms and management of adult HPP.
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Affiliation(s)
- Se-Min Kim
- Center for Translational Medicine and Pharmacological Science, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Funda Korkmaz
- Center for Translational Medicine and Pharmacological Science, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Steve Sims
- Center for Translational Medicine and Pharmacological Science, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Vitaly Ryu
- Center for Translational Medicine and Pharmacological Science, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Tony Yuen
- Center for Translational Medicine and Pharmacological Science, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Mone Zaidi
- Center for Translational Medicine and Pharmacological Science, Icahn School of Medicine at Mount Sinai, New York, NY, USA
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11
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Shen NW, Yi LG, Omesiete W, Peroutka CM, Raghavan SS, Greer KE. Cutaneous lesions in the setting of hypophosphatasia. JAAD Case Rep 2023; 42:23-25. [PMID: 37965189 PMCID: PMC10641551 DOI: 10.1016/j.jdcr.2023.10.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2023] Open
Affiliation(s)
- Nancy W. Shen
- University of Virginia School of Medicine, Charlottesville, Virginia
| | - Lauren G. Yi
- University of Virginia Department of Dermatology, Charlottesville, Virginia
| | - Wilson Omesiete
- University of Virginia Department of Dermatology, Charlottesville, Virginia
| | | | - Shyam S. Raghavan
- University of Virginia Department of Pathology, Charlottesville, Virginia
| | - Kenneth E. Greer
- University of Virginia Department of Dermatology, Charlottesville, Virginia
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12
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Pendleton EG, Nichenko AS, Mcfaline-Figueroa J, Raymond-Pope CJ, Schifino AG, Pigg TM, Barrow RP, Greising SM, Call JA, Mortensen LJ. Compromised Muscle Properties in a Severe Hypophosphatasia Murine Model. Int J Mol Sci 2023; 24:15905. [PMID: 37958888 PMCID: PMC10649932 DOI: 10.3390/ijms242115905] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Revised: 10/23/2023] [Accepted: 10/26/2023] [Indexed: 11/15/2023] Open
Abstract
Hypophosphatasia (HPP) is a rare metabolic bone disorder characterized by low levels of tissue non-specific alkaline phosphatase (TNAP) that causes under-mineralization of the bone, leading to bone deformity and fractures. In addition, patients often present with chronic muscle pain, reduced muscle strength, and an altered gait. In this work, we explored dynamic muscle function in a homozygous TNAP knockout mouse model of severe juvenile onset HPP. We found a reduction in skeletal muscle size and impairment in a range of isolated muscle contractile properties. Using histological methods, we found that the structure of HPP muscles was similar to healthy muscles in fiber size, actin and myosin structures, as well as the α-tubulin and mitochondria networks. However, HPP mice had significantly fewer embryonic and type I fibers than wild type mice, and fewer metabolically active NADH+ muscle fibers. We then used oxygen respirometry to evaluate mitochondrial function and found that complex I and complex II leak respiration were reduced in HPP mice, but that there was no disruption in efficiency of electron transport in complex I or complex II. In summary, the severe HPP mouse model recapitulates the muscle strength impairment phenotypes observed in human patients. Further exploration of the role of alkaline phosphatase in skeletal muscle could provide insight into mechanisms of muscle weakness in HPP.
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Affiliation(s)
- Emily G. Pendleton
- Regenerative Bioscience Center, Rhodes Center for ADS, University of Georgia, Athens, GA 30602, USA
| | - Anna S. Nichenko
- Regenerative Bioscience Center, Rhodes Center for ADS, University of Georgia, Athens, GA 30602, USA
- Department of Physiology & Pharmacology, University of Georgia, Athens, GA 30602, USA
| | - Jennifer Mcfaline-Figueroa
- Regenerative Bioscience Center, Rhodes Center for ADS, University of Georgia, Athens, GA 30602, USA
- Department of Physiology & Pharmacology, University of Georgia, Athens, GA 30602, USA
| | | | - Albino G. Schifino
- Regenerative Bioscience Center, Rhodes Center for ADS, University of Georgia, Athens, GA 30602, USA
- Department of Physiology & Pharmacology, University of Georgia, Athens, GA 30602, USA
| | - Taylor M. Pigg
- Regenerative Bioscience Center, Rhodes Center for ADS, University of Georgia, Athens, GA 30602, USA
| | - Ruth P. Barrow
- Regenerative Bioscience Center, Rhodes Center for ADS, University of Georgia, Athens, GA 30602, USA
| | - Sarah M. Greising
- School of Kinesiology, University of Minnesota, Minneapolis, MN 55455, USA
| | - Jarrod A. Call
- Regenerative Bioscience Center, Rhodes Center for ADS, University of Georgia, Athens, GA 30602, USA
- Department of Physiology & Pharmacology, University of Georgia, Athens, GA 30602, USA
| | - Luke J. Mortensen
- Regenerative Bioscience Center, Rhodes Center for ADS, University of Georgia, Athens, GA 30602, USA
- Department of Physiology & Pharmacology, University of Georgia, Athens, GA 30602, USA
- School of Chemical, Materials and Biomedical Engineering, University of Georgia, Athens, GA 30602, USA
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13
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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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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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15
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Rauf MA, Kotecha J, Moss K. Reducing diagnostic delay in hypophosphatasia: a case series of 14 patients presenting to general rheumatology. Osteoporos Int 2023; 34:1647-1652. [PMID: 37118032 PMCID: PMC10427523 DOI: 10.1007/s00198-023-06749-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: 11/06/2022] [Accepted: 04/05/2023] [Indexed: 04/30/2023]
Abstract
OBJECTIVES Hypophosphatasia (HPP) is a rare genetic metabolic bone disease that can cause chronic pain and fractures. Its hallmark is a persistently low serum ALP. HPP is now recognised by many osteoporosis specialists, but other specialists, such as rheumatologists and primary care physicians, may be less aware of this condition, causing diagnostic delay and possible harm to these patients. Our objective was to highlight features that can reduce this delay. METHODS We retrospectively analysed 14 patients that presented with musculoskeletal pain to general rheumatology clinic at St. George's Hospital and were subsequently diagnosed with HPP. RESULTS Median diagnostic delay was 13 years. All patients had an ALP below reference range for age and gender, with lowest mean ALP of 16 IU/L. All but one patient were women with median age of 51 years. Most common presentation was peripheral joint pain in 85.7% of patients. This was due to early-onset CPPD (calcium pyrophosphate deposition disease) in 71.4% of patients, osteoarthritis in 50%, or bursitis in 50%. Axial pain was reported in 64% of patients due to osteoarthritis or spinal stenosis. Fifty percent of patients had a history of long bone pain. Fifty percent had previous fracture(s). A total of 28.6% of patients had psoriatic arthritis, of which 1 patient had spondyloarthropathy, and 4 patients also had enthesitis. CONCLUSION Patients with HPP can present to rheumatology with musculoskeletal pain, and if a persistently low ALP is confirmed, this may reduce the diagnostic delay of this rare disease. Similar to other rheumatologic patients, musculoskeletal pain in HPP was noted in peripheral joints and in the spine with almost a third of patients having psoriatic arthritis. Pain was also noted in the long bones, a feature consistent with metabolic bone disease. The diagnosis of HPP was also more likely in those patients with a personal or family history of dental disease or arthritis.
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Affiliation(s)
- Muhammad A. Rauf
- Department of Medicine, St. George’s University of London, Cranmer Terrace, London, SW17 0RE UK
| | - Jalpa Kotecha
- Weston Education Centre, King’s College Hospital, London, UK
| | - Katie Moss
- Department of Rheumatology, St. George’s University Hospitals NHS Foundation Trust, London, UK
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16
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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: 2.0] [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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Kang M, Wu M, Crane JL. Asfotase alfa improved skeletal mineralization and fracture healing in a child with MCAHS. Bone 2023; 172:116778. [PMID: 37088336 DOI: 10.1016/j.bone.2023.116778] [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: 02/16/2023] [Revised: 04/06/2023] [Accepted: 04/18/2023] [Indexed: 04/25/2023]
Abstract
Tissue non-specific alkaline phosphatase (TNSALP) is an enzyme that is tethered to the cell membrane by glycosylphosphatidylinositol (GPI) and converts inorganic pyrophosphate to inorganic phosphate. Inorganic phosphate combines with calcium to form hydroxyapatite, the main mineral in the skeleton. When TNSALP is defective, conversion of inorganic pyrophosphate to inorganic phosphate is impaired and the skeleton is at risk of under-mineralization. Phosphatidylinositol glycan anchor biosynthesis class N (PIGN) is one of >20 genes in in the GPI-biosynthesis family. Pathogenic variants in PIGN have been identified in multiple congenital anomalies-hypotonia-seizures syndrome (OMIM 614080), although a metabolic bone disease or skeletal fragility phenotype has not been reported. We describe a female child with multiple congenital anomalies-hypotonia-seizures syndrome due to a compound heterozygous pathogenic variant in PIGN who sustained a low-trauma distal femur fracture at age 7.4 years. We hypothesized that the GPI synthesis defect may result in metabolic bone disease from inadequate anchoring of TNSALP in bone and initiated asfotase alfa, a human bone-targeted recombinant TNSALP-Fc-deca-aspartate peptide, as it could bypass the PIGN genetic defect that possibly caused her skeletal fragility. Asfotase alfa was begun at 8.5 years. Baseline X-rays revealed mild rachitic findings of wrists and knees, which resolved by 5 months of treatment. Bone mineral density (BMD) assessed by dual-energy X-ray absorptiometry (DXA) showed mild improvement in spine, hip and total body less head after 16 months of treatment, while radius declined. She sustained additional low trauma fractures at right tibia and left humeral neck at 11 and 15 months into treatment, which healed quickly. Calcium, phosphorus, and parathyroid hormone levels have remained within the normal range over the 18 months of treatment. For adverse effect, she experienced a rash and discomfort in the first week of treatment which resolved with ibuprofen and diphenhydramine. She also developed subcutaneous fat atrophy. Overall, in this child with a compound pathogenic variant in PIGN, off-label use of asfotase alfa has been generally well tolerated with minimal side effects and resolution of rickets, but she continues to remain skeletally fragile.
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Affiliation(s)
- Min Kang
- Division of Endocrinology, Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Malinda Wu
- Division of Endocrinology, Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Janet L Crane
- Division of Endocrinology, Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
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18
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Khursigara G, Huertas P, Wenkert D, O'Brien K, Sabbagh Y. Effects of food, fasting, and exercise on plasma pyrophosphate levels and ENPP1 activity in healthy adults. Bone 2023; 171:116750. [PMID: 37003563 DOI: 10.1016/j.bone.2023.116750] [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: 08/30/2022] [Revised: 03/21/2023] [Accepted: 03/23/2023] [Indexed: 04/01/2023]
Abstract
BACKGROUND Inorganic pyrophosphate (PPi) is highly regulated as it plays a critical role in the regulation of physiological mineralization. Dysregulation of plasma PPi is associated with skeletal hypomineralization and pathogenic mineralization in soft connective tissue, arteries, and heart valves. There is no standard approach to measuring PPi, making it difficult to establish PPi as a biomarker of mineralization disorders. This study aims to determine the impact of time of day, meals, or exercise on plasma PPi homeostasis using a highly sensitive PPi assay. METHODS In this single-center trial, a clinical laboratory improvement amendment (CLIA) validated modified sulfurylase-based adenosine 5-triphosphate (ATP) assay was used to measure PPi levels throughout the day in 10 healthy adults under 3 conditions; normal diet (non-fasting), fasting, and normal diet with exercise. Serum ectonucleotide pyrophosphatase/phosphodiesterase 1 activity (ENPP1; an enzyme that produces PPi) was also measured to determine whether these conditions influence PPi levels through ENPP1 activity. RESULTS There is a circadian increase in mean PPi levels under fasting and non-fasting conditions between 8 am and 6 pm, followed by a rapid return to baseline overnight. A circadian increase in ENPP1 activity was also measured under fasting but was lost under non-fasting conditions. Meals increased the individual variability of PPi levels when compared to the same individual fasting. PPi levels and ENPP1 activity exhibited a short-term increase after intense exercise. We found PPi ranges from 1465 nM to 2969 nM (mean 2164 nM) after fasting overnight. Within this range, there was lower intra-subject variability in PPi, suggesting that each individual has a uniquely regulated normal PPi range. CONCLUSION Plasma levels of PPi can be reliably measured after an overnight fast and show promise as a biomarker of mineralization disorders.
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Affiliation(s)
- Gus Khursigara
- Inozyme Pharma, 321 Summer St, Suite 400, Boston, MA 02201, United States of America.
| | - Pedro Huertas
- Inozyme Pharma, 321 Summer St, Suite 400, Boston, MA 02201, United States of America
| | - Deborah Wenkert
- Inozyme Pharma, 321 Summer St, Suite 400, Boston, MA 02201, United States of America
| | - Kevin O'Brien
- Inozyme Pharma, 321 Summer St, Suite 400, Boston, MA 02201, United States of America
| | - Yves Sabbagh
- Inozyme Pharma, 321 Summer St, Suite 400, Boston, MA 02201, United States of America
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19
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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: 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: 08/29/2022] [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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20
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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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Childhood Hypophosphatasia Associated with a Novel Biallelic ALPL Variant at the TNSALP Dimer Interface. Int J Mol Sci 2022; 24:ijms24010282. [PMID: 36613725 PMCID: PMC9820760 DOI: 10.3390/ijms24010282] [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] [Received: 11/11/2022] [Revised: 12/08/2022] [Accepted: 12/15/2022] [Indexed: 12/28/2022] Open
Abstract
The goal of this study was to perform a clinical and molecular investigation in an eight-year-old female child diagnosed with hypophosphatasia (HPP). The proband and her family were evaluated by medical and dental histories, biochemical analyses, radiographic imaging, and genetic analysis of the tissue-nonspecific alkaline phosphatase (ALPL) gene. A bioinformatic analysis was performed to predict the structural and functional impact of the point mutations in the tissue-nonspecific alkaline phosphatase (TNSALP) molecule and to define their potential contribution to the phenotype. We identified a novel combination of heterozygous ALPL missense variants in the proband, p.Ala33Val and p.Asn47His, compatible with an autosomal recessive mode of inheritance and resulting in skeletal and dental phenotypes. Computational modeling showed that the affected Asn47 residue is located in the coil structure close to the N-terminal α-helix, whereas the affected Ala33 residue is localized in the N-terminal α-helix. Both affected residues are located close to the homodimer interface, suggesting they may impair TNSALP dimer formation and stability. Clinical and biochemical follow-up revealed improvements after six years of ERT. Reporting this novel combination of ALPL variants in childhood HPP provides new insights into genotype-phenotype associations for HPP and specific sites within the TNSALP molecule potentially related to a childhood-onset HPP and skeletal and dental manifestations. Beneficial effects of ERT are implicated in skeletal and dental tissues.
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22
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Sadhukhan S, Mehta P, Rajender S, Gupta SK, Chattopadhyay N. Proposing a clinical algorithm for better diagnosis of hypophosphatasia in resource-limiting situations. Osteoporos Int 2022; 33:2479-2493. [PMID: 35776147 DOI: 10.1007/s00198-022-06480-1] [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: 01/07/2022] [Accepted: 06/16/2022] [Indexed: 10/17/2022]
Abstract
Early diagnosis of hypophosphatasia (HPP) is challenging. Here, we propose to broaden the diagnostic criteria of HPP by reviewing published data on BMD and fractures in HPP patients. Non-osteoporotic fractures and higher than normal lumbar BMD were recurrent in HPP patients and could be included as diagnostic criteria. HPP is a genetic disorder caused by autosomal recessive or dominant loss-of-function mutations in the ALPL gene that encodes for tissue-nonspecific alkaline phosphatase (TNSALP). Expressive genetic heterogeneity and varying severity of TNSALP deficiency lead to a wide-ranging presentation of skeletal diseases at different ages that coupled with HPP's rarity and limitation of biochemical and mutational studies present serious hurdles to early diagnosis and management of HPP. To widen the scope of HPP diagnosis, we assessed the possibility of areal bone mineral density (BMD) as an additional clinical feature of this disease. PubMed, Web of Science, and ScienceDirect were searched with the following keywords: ("Hypophosphatasia OR HPP") AND ("Bone Mineral Density OR BMD") AND "Human". Studies and case reports of subjects with age ≥ 18 years and having BMD data were included. We pooled data from 25 publications comprising 356 subjects (90 males, 266 females). Only four studies had a control group. Biochemical hallmarks, pyridoxal 5'-phosphate (PLP) and phosphoethanolamine (PEA), were reported in fifteen and six studies, respectively. Twenty studies reported genetic data, nineteen studies reported non-vertebral fractures, all studies reported lumbar spine (LS) BMD, and nineteen reported non-vertebral BMD. Higher than normal and normal BMD at LS were reported in three and two studies, respectively. There was marked heterogeneity in BMD at the non-vertebral sites. Higher than normal or normal LS BMD in an adult with minimal or insufficient fractures, pseudofractures, non-healing fractures, fragility fractures, and stress fractures may be included in the diagnostic protocol of HPP. However, genetic testing is recommended for a definitive diagnosis.
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Affiliation(s)
- Sreyanko Sadhukhan
- Division of Endocrinology and Centre for Research in Anabolic Skeletal Targets in Health and Illness (ASTHI), CSIR-Central Drug Research Institute, Lucknow, India
- Academy of Scientific and Innovative Research, Ghaziabad, 201002, India
| | - Poonam Mehta
- Division of Endocrinology and Centre for Research in Anabolic Skeletal Targets in Health and Illness (ASTHI), CSIR-Central Drug Research Institute, Lucknow, India
- Academy of Scientific and Innovative Research, Ghaziabad, 201002, India
| | - Singh Rajender
- Division of Endocrinology and Centre for Research in Anabolic Skeletal Targets in Health and Illness (ASTHI), CSIR-Central Drug Research Institute, Lucknow, India
- Academy of Scientific and Innovative Research, Ghaziabad, 201002, India
| | - Sushil Kumar Gupta
- Department of Endocrinology, Sanjay Gandhi Post-Graduate Institute of Medical Sciences, Lucknow, India
| | - Naibedya Chattopadhyay
- Division of Endocrinology and Centre for Research in Anabolic Skeletal Targets in Health and Illness (ASTHI), CSIR-Central Drug Research Institute, Lucknow, India.
- Academy of Scientific and Innovative Research, Ghaziabad, 201002, India.
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23
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Impact of discontinuing 5 years of enzyme replacement treatment in a cohort of 6 adults with hypophosphatasia: A case series. Bone Rep 2022; 17:101617. [PMID: 36097602 PMCID: PMC9463174 DOI: 10.1016/j.bonr.2022.101617] [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: 06/17/2022] [Revised: 08/26/2022] [Accepted: 08/28/2022] [Indexed: 11/20/2022] Open
Abstract
Asfotase alfa is a human recombinant enzyme replacement therapy for hypophosphatasia. We describe 6 adults who were treated with asfotase alfa for 61–68 months in a clinical trial (NCT01163149), after which asfotase alfa was discontinued for 15–48 months. The patients experienced clinical deterioration and, when treatment was restarted, showed improvement. Patients with hypophosphatasia should be closely monitored if asfotase alfa is stopped as clinical decline is likely. Clinical practice guidelines are needed. Discontinuation of asfotase alfa results in deterioration of hypophosphatasia. Discontinuation of asfotase alfa results in worse pain scores. Reinitiation of asfotase alfa is associated with clinical and biochemical improvement.
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24
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Beck NM, Sagaser KG, Lawson CS, Hertenstein C, Jachens A, Forster KR, Miller KA, Jelin AC, Blakemore KJ, Hoover‐Fong J. Not just a carrier: Clinical presentation and management of patients with heterozygous disease-causing alkaline phosphatase (ALPL) variants identified through expanded carrier screening. Mol Genet Genomic Med 2022; 11:e2056. [PMID: 36444396 PMCID: PMC9834184 DOI: 10.1002/mgg3.2056] [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: 01/21/2022] [Revised: 07/05/2022] [Accepted: 09/01/2022] [Indexed: 12/02/2022] Open
Abstract
Hypophosphatasia (HPP) is an underrecognized, complex bone mineralization disorder with variable manifestations caused by one or two deleterious variants in the alkaline phosphatase (ALPL) gene. Expanded carrier screening (ECS), inclusive of ALPL, intends to inform reproductive risk but may incidentally reveal an HPP diagnosis with 50% familial risks. We sought to investigate at-risk individuals and develop a multidisciplinary referral and evaluation protocol for ECS-identified ALPL heterozygosity. A retrospective database query of ECS results from 8 years to 1 month for heterozygous pathogenic/likely pathogenic ALPL variants was completed. We implemented a clinical protocol for diagnostic testing and imaging, counseling, and interdisciplinary care management for identified patients, and outcomes were documented. Heterozygous ALPL variants were identified in 12/2248 unrelated patients undergoing ECS (0.53%; heterozygote frequency 1/187). Of 10 individuals successfully contacted, all demonstrated symptomatology and/or alkaline phosphatase values consistent with HPP. ECS may reveal incidental health risks, including recognition of missed HPP diagnoses in ALPL heterozygotes. In our cohort, all ECS-identified ALPL heterozygotes with clinical and/or biochemical data available demonstrated features of HPP. Referral to a genetics professional familiar with HPP is indicated for family history assessment, genetic counseling, cascade testing, and long-term bone health management.
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Affiliation(s)
- Natalie M. Beck
- Greenberg Center for Skeletal Dysplasias, Department Genetic of MedicineJohns Hopkins University School of MedicineBaltimoreMarylandUSA,Genome Medical ServicesSan FranciscoCaliforniaUSA
| | - Katelynn G. Sagaser
- Division of Maternal Fetal Medicine, Department of Gynecology and ObstetricsJohns Hopkins University School of MedicineBaltimoreMarylandUSA,JunoDxSan DiegoCaliforniaUSA
| | - Cathleen S. Lawson
- Division of Maternal Fetal Medicine, Department of Gynecology and ObstetricsJohns Hopkins University School of MedicineBaltimoreMarylandUSA
| | - Christine Hertenstein
- Division of Maternal Fetal Medicine, Department of Gynecology and ObstetricsJohns Hopkins University School of MedicineBaltimoreMarylandUSA
| | - Ashley Jachens
- Center for Maternal and Fetal MedicineHoward County General Hospital, Johns Hopkins HospitalBaltimoreMarylandUSA
| | - Katherine R. Forster
- Center for Fetal TherapyJohns Hopkins University School of MedicineBaltimoreMarylandUSA,Sibley Memorial Hospital Maternal Fetal MedicineWashingtonDistrict of ColumbiaUSA
| | - Kristen A. Miller
- Division of Maternal Fetal Medicine, Department of Gynecology and ObstetricsJohns Hopkins University School of MedicineBaltimoreMarylandUSA
| | - Angie C. Jelin
- Division of Maternal Fetal Medicine, Department of Gynecology and ObstetricsJohns Hopkins University School of MedicineBaltimoreMarylandUSA
| | - Karin J. Blakemore
- Division of Maternal Fetal Medicine, Department of Gynecology and ObstetricsJohns Hopkins University School of MedicineBaltimoreMarylandUSA
| | - Julie Hoover‐Fong
- Greenberg Center for Skeletal Dysplasias, Department Genetic of MedicineJohns Hopkins University School of MedicineBaltimoreMarylandUSA
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25
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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: 5] [Impact Index Per Article: 2.5] [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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26
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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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27
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Khanjee N, Maalouf NM. Romosozumab-aqqg in the Treatment of Osteoporosis in a Patient With Hypophosphatasia. J Endocr Soc 2022; 6:bvac159. [DOI: 10.1210/jendso/bvac159] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Indexed: 11/11/2022] Open
Abstract
Abstract
Hypophosphatasia is a rare, inherited condition that causes osteomalacia and recurrent fractures. Therapeutic options for osteoporosis in patients with hypophosphatasia are limited because of concerns for a greater likelihood of atypical femoral fractures with antiresorptive agents. We report here the case of a patient with hypophosphatasia and osteoporosis who was treated with romosozumab-aqqg (Romo). An 81-year-old woman presented for management of osteoporosis with multiple fractures. She experienced a decline in bone mineral density over 20 years despite sequential osteoporosis treatment with oral bisphosphonates, hormone replacement therapy, teriparatide, and denosumab. Hypophosphatasia was suspected because of low serum alkaline phosphatase levels and was confirmed by genetic testing. After diagnosing hypophosphatasia, bone mineral density continued to decline and a trial of Romo was begun. After 1 year of Romo therapy, bone mineral density improved by 21%, and 10% at the lumbar spine and total hip, respectively. These changes were substantially greater than what she had experienced with prior teriparatide therapy. Blood alkaline phosphatase remained low on Romo. To our knowledge, this is the first report of a patient with hypophosphatasia and osteoporosis treated with Romo. In our patient, Romo did not significantly impact serum alkaline phosphatase, but improved bone mineral density significantly. In conclusion, Romo is a potential treatment option for osteoporosis in patients with hypophosphatasia for whom limited alternatives exist.
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Affiliation(s)
- Naveed Khanjee
- Department of Internal Medicine, Division of Endocrinology, University of Texas Southwestern Medical Center , Dallas, TX 75390-8885 , USA
| | - Naim M Maalouf
- Department of Internal Medicine, Division of Endocrinology, University of Texas Southwestern Medical Center , Dallas, TX 75390-8885 , USA
- The Charles and Jane Pak Center for Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center , Dallas, TX 75390-8885 , USA
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28
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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: 0] [Impact Index Per Article: 0] [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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29
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Reprogramming of Hypophosphatasia patient cells to generate a new human iPSC cell line (UOMi009-A). Stem Cell Res 2022; 64:102921. [PMID: 36152425 DOI: 10.1016/j.scr.2022.102921] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 09/15/2022] [Accepted: 09/16/2022] [Indexed: 11/23/2022] Open
Abstract
In this study we report reprogramming and generation of a new human induced pluripotent stem cell line UOMi009_A, which was generated from a 64 year old male patient with childhood onset Hypophosphatasia (HPP). The patient has compound heterozygous mutations in the ALPL gene (c.571G>A (p.Glu191Lys) and c.1001G>A (p.Gly334Asp)) which were confirmed in the UOMi009_A line. This line was well characterized and will help in our future assessment of HPP disease pathophysiology and drug screening.
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30
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Sinha P, Gabor R, Haupt‐Harrington R, Deering L, Steiner RD. Dental manifestations in adult hypophosphatasia and their correlation with biomarkers. JIMD Rep 2022; 63:434-445. [PMID: 36101824 PMCID: PMC9458606 DOI: 10.1002/jmd2.12307] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2022] [Revised: 05/02/2022] [Accepted: 05/24/2022] [Indexed: 11/18/2022] Open
Abstract
Hypophosphatasia (HPP) is a genetic condition with broad clinical manifestations caused by alkaline phosphatase (ALP) deficiency. Adults with HPP exhibit a wide spectrum of signs and symptoms. Dental manifestations including premature tooth loss are common. Much of the published literature reporting dental manifestations consists of case reports and series of symptomatic patients, likely biased towards more severe dental manifestations. The objective of this study was to systematically explore the dental manifestations among adults with HPP by conducting a comprehensive dental evaluation. To minimize bias, the study explored dental manifestations in an unselected cohort of adults with HPP. Participants were identified searching electronic health record (EHR) data from a rural health system to discover adults with persistent ALP deficiency. Heterozygotes with pathogenic (P), likely pathogenic (LP), or uncertain variants (VUS) in ALPL and at least one elevated ALP substrate were defined as adults with HPP and underwent genetic, dental, oral radiographic, and biomarker evaluation. Twenty‐seven participants completed the study. Premature tooth loss was present in 63% (17/27); 19% (5/27) were missing eight or more teeth. Statistically significant associations were found between premature permanent tooth loss and HPP biomarkers ALP (p = 0.049) and bone‐specific ALP (p = 0.006). Serum ALP (ρ = −0.43, p = 0.037) and bone‐specific ALP (ρ = −0.57, p = 0.004) were negatively correlated with number of teeth lost prematurely. As noted with tooth loss, periodontal breakdown was associated with bone‐specific ALP. An inverse association between periodontal breakdown and bone‐specific ALP was observed (p = 0.014). These findings suggest a role for ALP in maintenance of dentition.
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Affiliation(s)
- Priya Sinha
- Marshfield Clinic Health System Marshfield Dental Center Marshfield Wisconsin USA
| | - Rachel Gabor
- Marshfield Clinic Research Institute Research Computing and Analytics Marshfield Wisconsin USA
| | - Rachael Haupt‐Harrington
- Marshfield Clinic Health System, Marshfield Clinic Research Institute Medical Genetics Marshfield Wisconsin
| | - Leila Deering
- Marshfield Clinic Research Institute Research Computing and Analytics Marshfield Wisconsin USA
| | - Robert D. Steiner
- Marshfield Clinic Health System, Marshfield Clinic Research Institute Medical Genetics Marshfield Wisconsin
- University of Wisconsin School of Medicine and Public Health Madison Wisconsin
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31
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Dahir KM, Seefried L, Kishnani PS, Petryk A, Högler W, Linglart A, Martos-Moreno GÁ, Ozono K, Fang S, Rockman-Greenberg C. Clinical profiles of treated and untreated adults with hypophosphatasia in the Global HPP Registry. Orphanet J Rare Dis 2022; 17:277. [PMID: 35854311 PMCID: PMC9295501 DOI: 10.1186/s13023-022-02393-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Accepted: 06/06/2022] [Indexed: 11/10/2022] Open
Abstract
Background The clinical signs and symptoms of hypophosphatasia (HPP) can manifest during any stage of life. The age at which a patient’s symptoms are reported can impact access to targeted treatment with enzyme replacement therapy (asfotase alfa), as this treatment is indicated for patients with pediatric-onset HPP in most countries. As such, many patients reported to have adult-onset HPP typically do not receive treatment. Comparison of the disease in treated and untreated adult patients is confounded by the approved indication. To avoid this confounding factor, a comparison between baseline disease manifestations prominent among treated versus untreated adult patients was limited to those with pediatric-onset HPP using data collected from the Global HPP Registry. The hypothesis was that treated adults will have a greater disease burden at baseline than untreated adults. The analysis of disease manifestations in adults with adult-onset HPP was conducted separately. Results A total of 398 adults with HPP were included; 213 with pediatric-onset (114 treated, 99 untreated) and 141 with adult-onset HPP (2 treated and 139 untreated). The treated, pediatric-onset patients were more likely to have a history of pain (prevalence ratio [PR]: 1.3, 95% confidence interval [CI] 1.1, 1.4), skeletal (PR: 1.3, 95% CI 1.1, 1.6), constitutional/metabolic (PR: 1.7, 95% CI 1.3, 2.0), muscular (PR: 1.8, 95% CI 1.4, 2.1) and neurological (PR: 1.7, 95% CI 1.1, 2.3) manifestations of HPP, and also had poorer measures for health-related quality of life, pain, and disability compared with untreated pediatric-onset patients. In patients with adult-onset HPP, the most frequent signs and symptoms were chronic bone pain (52.5%), dental manifestations (42.6%), fatigue (23.4%), recurrent fractures or pseudofractures (22.0%), and generalized body pain (22.0%). Conclusions Along with the more classical skeletal signs and symptoms, pain, muscular, and constitutional/metabolic manifestations are common in adults with HPP, regardless of age of disease onset, highlighting a full spectrum of HPP manifestations.
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Affiliation(s)
- Kathryn M Dahir
- Program for Metabolic Bone Disorders at Vanderbilt, Endocrinology and Diabetes, Vanderbilt University Medical Center, 8210 Medical Center East, 1215 21st Avenue South, Nashville, TN, 37232-8148, USA.
| | | | | | - Anna Petryk
- Alexion, AstraZeneca Rare Disease, Boston, MA, USA
| | - Wolfgang Högler
- Department of Paediatrics and Adolescent Medicine, Johannes Kepler University Linz, Linz, Austria.,Institute of Metabolism and Systems Research, University of Birmingham, Birmingham, UK
| | - Agnès Linglart
- DMU 3 SEA, Service d'endocrinologie et Diabète de L'enfant, filière OSCAR, Centre de Référence des Maladies Rares du Métabolisme du Calcium et du Phosphate, Paris-Saclay University, AP-HP, INSERM, Bicêtre Paris-Saclay Hospital, Le Kremlin-Bicêtre, France
| | - Gabriel Ángel Martos-Moreno
- Departments of Pediatrics and Pediatric Endocrinology Hospital Infantil, CIBERobn, ISCIII, Universitario Niño Jesús, IIS La Princesa, Universidad Autónoma de Madrid, Madrid, Spain
| | | | - Shona Fang
- Alexion, AstraZeneca Rare Disease, Boston, MA, 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: 0.5] [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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Bickford BW, Bennett S, Markert RJ. Not Your Typical Bisphosphonate Intolerance: A Case of Unusual Bone Pain With Low Alkaline Phosphatase. Cureus 2022; 14:e23163. [PMID: 35444911 PMCID: PMC9009988 DOI: 10.7759/cureus.23163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/08/2022] [Indexed: 12/03/2022] Open
Abstract
Bisphosphonates, first-line medications for osteoporosis, are often not tolerated or discontinued for multiple reasons. Hypophosphatasia (HPP) is a genetic deficiency with the enzyme activity of tissue-nonspecific alkaline phosphatase (TNSALP). The symptoms of adult HPP are often non-specific, and the diagnosis may be delayed for years. Low serum alkaline phosphatase, a hallmark feature of HPP, is often overlooked. Genetic testing is recommended to confirm diagnosis, and treatment with asfotase alfa, a recombinant alkaline phosphatase, is available for patients with HPP. We report a case of HPP in a 71-year-old female with recurrent skeletal pain and bisphosphonate intolerance who ultimately was diagnosed with HPP.
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Koga M, Kinoshita Y, Kato H, Kobayashi H, Shinoda Y, Nangaku M, Makita N, Dahir KM, Ito N. Massive calcification around large joints in a patient subsequently diagnosed with adult-onset hypophosphatasia. Osteoporos Int 2022; 33:505-509. [PMID: 34494146 DOI: 10.1007/s00198-021-06145-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Accepted: 09/02/2021] [Indexed: 10/20/2022]
Abstract
We report a 64-year-old Japanese woman with a history of progressive loss of motor function and painful swelling of large joints. At the age of 54, profound calcification appeared around the shoulder and hip joints, which did not heal after repeated surgical resections. Iliac bone biopsy revealed osteomalacic changes. Laboratory data showed low serum alkaline phosphatase (ALP) activity and a high urine phosphoethanolamine (PEA) concentration with normal serum calcium, phosphate, and fibroblast growth factor 23 (FGF23) levels. Subsequent genetic analysis of the ALPL gene confirmed the diagnosis of hypophosphatasia (HPP) with the identification of a heterozygous single nucleotide deletion, c.1559delT (p.Leu520ArgfsX86). We started a mineral-targeted enzyme replacement therapy, asfotase alfa (AA), to treat the patient's musculoskeletal symptoms. A follow-up bone biopsy after 12 months of AA treatment showed improvement of osteomalacia. Calcified deposits around the large joints were unchanged radiographically. To our knowledge, this is the first report of a patient with an adult-onset HPP who presented with profound calcification around multiple joints. Nonspecific clinical signs and symptoms in patients with adult-onset HPP often result in delayed diagnosis or misdiagnosis. We propose that bone biopsy and genetic analysis should be considered along with laboratory analysis for all patients with ectopic calcification around joints of unknown etiology for accurate diagnosis and better treatment.
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Affiliation(s)
- M Koga
- Division of Nephrology and Endocrinology, The University of Tokyo Hospital, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan
| | - Y Kinoshita
- Division of Nephrology and Endocrinology, The University of Tokyo Hospital, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan
| | - H Kato
- Division of Nephrology and Endocrinology, The University of Tokyo Hospital, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan
| | - H Kobayashi
- Department of Orthopedic Surgery, The University of Tokyo Hospital, Tokyo, Japan
| | - Y Shinoda
- Department of Rehabilitation Medicine, The University of Tokyo Hospital, Tokyo, Japan
| | - M Nangaku
- Division of Nephrology and Endocrinology, The University of Tokyo Hospital, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan
| | - N Makita
- Division of Nephrology and Endocrinology, The University of Tokyo Hospital, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan
| | - K M Dahir
- Vanderbilt University Medical Center, Program for Metabolic Bone Disorders, Nashville, TN, USA
| | - N Ito
- Division of Nephrology and Endocrinology, The University of Tokyo Hospital, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan.
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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: 0.5] [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: 2] [Impact Index Per Article: 1.0] [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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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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Guarnieri V, Sileri F, Indirli R, Guabello G, Longhi M, Dito G, Verdelli C, Corbetta S. Clinical, biochemical and genetic findings in adult patients with chronic hypophosphatasemia. J Endocrinol Invest 2022; 45:125-137. [PMID: 34213743 PMCID: PMC8741696 DOI: 10.1007/s40618-021-01625-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Accepted: 06/24/2021] [Indexed: 11/04/2022]
Abstract
PURPOSE The study aimed to define the clinical, biochemical and genetic features of adult patients with osteopenia/osteoporosis and/or bone fragility and low serum alkaline phosphatase (sALP). METHODS Twenty-two patients with at least two sALP values below the reference range were retrospectively enrolled after exclusion of secondary causes. Data about clinical features, mineral and bone markers, serum pyridoxal-5'-phosphate (PLP), urine phosphoethanolamine (PEA), lumbar and femur bone densitometry, and column X-ray were collected. Peripheral blood DNA of each participant was analyzed to detect ALPL gene anomalies. RESULTS Pathogenic ALPL variants (pALPL) occurred in 23% and benign variants in 36% of patients (bALPL), while nine patients harbored wild-type alleles (wtALPL). Fragility fractures and dental anomalies were more frequent in patients harboring pALPL and bALPL than in wtALPL patients. Of note, wtALPL patients comprised women treated with tamoxifen for hormone-sensitive breast cancer. Mineral and bone markers were similar in the three groups. Mean urine PEA levels were significantly higher in patients harboring pALPL than those detected in patients harboring bALPL and wtALPL; by contrast, serum PLP levels were similar in the three groups. A 6-points score, considering clinical and biochemical features, was predictive of pALPL detection [P = 0.060, OR 1.92 (95% CI 0.972, 3.794)], and more significantly of pALPL or bALPL [P = 0.025, OR 14.33 (95% CI 1.401, 14.605)]. CONCLUSION In osteopenic/osteoporotic patients, single clinical or biochemical factors did not distinguish hypophosphatasemic patients harboring pALPL or bALPL from those harboring wtALPL. Occurrence of multiple clinical and biochemical features is predictive of ALPL anomalies, and, therefore, they should be carefully identified. Tamoxifen emerged as a hypophosphatasemic drug.
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Affiliation(s)
- V Guarnieri
- Division of Medical Genetics, Fondazione IRCCS Ospedale Casa Sollievo Sofferenza, San Giovanni Rotondo, Foggia, Italy
| | - F Sileri
- Lab of Endocrine and Metabolic Research, Department of Endocrine and Metabolic Diseases, IRCCS Istituto Auxologico Italiano, Milan, Italy
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
| | - R Indirli
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
- Endocrinology Unit, Fondazione IRCCS Cà Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - G Guabello
- Reumatology Unit, IRCCS Istituto Ortopedico Galeazzi, Milan, Italy
| | - M Longhi
- Reumatology Unit, IRCCS Istituto Ortopedico Galeazzi, Milan, Italy
| | - G Dito
- Endocrinology and Diabetology Service, IRCCS Istituto Ortopedico Galeazzi, Milan, Italy
| | - C Verdelli
- Laboratory of Experimental Endocrinology, IRCCS Istituto Ortopedico Galeazzi, Milan, Italy
| | - S Corbetta
- Endocrinology and Diabetology Service, IRCCS Istituto Ortopedico Galeazzi, Milan, Italy.
- Department of Biochemical, Surgical and Dental Sciences, University of Milan, Milan, Italy.
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Seefried L, Rak D, Petryk A, Genest F. Bone turnover and mineral metabolism in adult patients with hypophosphatasia treated with asfotase alfa. Osteoporos Int 2021; 32:2505-2513. [PMID: 34215909 PMCID: PMC8608777 DOI: 10.1007/s00198-021-06025-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Accepted: 05/31/2021] [Indexed: 11/04/2022]
Abstract
UNLABELLED There is limited understanding of how asfotase alfa affects mineral metabolism and bone turnover in adults with pediatric-onset hypophosphatasia. This study showed that adults with hypophosphatasia treated with asfotase alfa experienced significant changes in biochemical markers of bone and mineral metabolism, possibly reflecting enhanced bone remodeling of previously osteomalacic bone. INTRODUCTION Hypophosphatasia (HPP), due to a tissue nonspecific alkaline phosphatase (TNSALP) deficiency, can cause impaired bone mineralization and turnover. Although HPP may be treated with asfotase alfa, an enzyme replacement therapy, limited data are available on how treatment with asfotase alfa affects mineral metabolism and bone turnover in adults with HPP. METHODS ALP substrates, bone turnover and mineral metabolism markers, and bone mineral density (BMD) data from EmPATHY, a single-center, observational study of adults (≥ 18 years) with pediatric-onset HPP treated with asfotase alfa (NCT03418389), were collected during routine clinical care and analyzed from baseline through 24 months of treatment. RESULTS Data from 21 patients showed significantly increased ALP activity and reduced urine phosphoethanolamine (PEA)/creatinine (Cr) ratios after baseline through 24 months of asfotase alfa treatment. There were significant transient increases in parathyroid hormone 1-84 (PTH), osteocalcin, and procollagen type 1 N-propeptide (P1NP) levels at 3 and 6 months and in tartrate-resistant acid phosphatase 5b (TRAP5b) levels at 3 months, with a significant decrease in N-terminal telopeptide of type 1 collagen (NTX) levels at 24 months. Lumbar spine BMD T scores continuously increased during treatment. CONCLUSION Significant changes in bone turnover and mineral metabolism markers after asfotase alfa treatment suggest that treatment-mediated mineralization may enable remodeling and bone turnover on previously unmineralized surfaces. Urine PEA/Cr ratios may be a useful parameter in monitoring treatment during routine care.
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Affiliation(s)
- L Seefried
- Orthopedic Clinic König-Ludwig-Haus, Julius-Maximilians-Universität Würzburg, Brettreichstr. 11, 97070, Würzburg, Germany.
| | - D Rak
- Orthopedic Clinic König-Ludwig-Haus, Julius-Maximilians-Universität Würzburg, Brettreichstr. 11, 97070, Würzburg, Germany
| | - A Petryk
- Alexion Pharmaceuticals, Inc., Boston, MA, USA
| | - F Genest
- Orthopedic Clinic König-Ludwig-Haus, Julius-Maximilians-Universität Würzburg, Brettreichstr. 11, 97070, Würzburg, Germany
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Abstract
Hypophosphatasia (HPP) is an inherited metabolic disease caused by loss-of-function mutations in the tissue non-specific alkaline phosphatase (TNAP) gene. Reduced activity of TNAP leads to the accumulation of its substrates, mainly inorganic pyrophosphate and pyridoxal-5′-phosphate, metabolic aberrations that largely explain the musculoskeletal and systemic features of the disease. More than 400 ALPL mutations, mostly missense, are reported to date, transmitted by either autosomal dominant or recessive mode. Severe disease is rare, with incidence ranging from 1:100,000 to 1:300,000 live births, while the estimated prevalence of the less severe adult form is estimated to be between 1:3100 to 1:508, in different countries in Europe. Presentation largely varies, ranging from death in utero to asymptomatic adults. In infants and children, clinical features include skeletal, respiratory and neurologic complications, while recurrent, poorly healing fractures, muscle weakness and arthropathy are common in adults. Persistently low serum alkaline phosphatase is the cardinal biochemical feature of the disease. Management requires a dedicated multidisciplinary team. In mild cases, treatment is usually symptomatic. Severe cases, with life-threating or debilitating complications, can be successfully treated with enzyme replacement therapy with asfotase alfa.
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Schroth RJ, Long C, Lee VHK, Alai-Towfigh H, Rockman-Greenberg C. Dental outcomes for children receiving asfotase alfa for hypophosphatasia. Bone 2021; 152:116089. [PMID: 34175501 DOI: 10.1016/j.bone.2021.116089] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Revised: 06/01/2021] [Accepted: 06/22/2021] [Indexed: 11/30/2022]
Abstract
INTRODUCTION Hypophosphatasia, a genetic disease impeding development of teeth and bones, is associated with premature exfoliation of primary teeth. Hypophosphatasia is caused by mutations in the ALPL gene, which encodes the tissue non-specific form of alkaline phosphatase. Asfotase alfa (Strensiq®) is a human recombinant bone-targeted alkaline phosphatase. OBJECTIVES To review development and exfoliation patterns of primary/permanent teeth in a cohort of patients with hypophosphatasia enrolled in an open-label clinical trial of enzyme replacement therapy (ERT) with asfotase alfa. METHODS Data were collected from existing study files of a cohort of patients ≤5 years of age with infantile hypophosphatasia. Children were recruited at the Winnipeg site of a global clinical trial and were treated with ERT. Dental information, including the exfoliation/eruption patterns, were recorded at each visit. RESULTS Eleven children (7 females, 4 males) participated. Participants enrolled as infants (5 infants; mean age 3.0 ± 2.3 months) prematurely lost significantly fewer teeth to hypophosphatasia than patients recruited as preschoolers (6 preschoolers; mean age 52.5 ± 11.3 months), who started on asfotase alfa at a later age. Conclusion The oral health of children with early onset infantile hypophosphatasia may be improved with early and continued administration of ERT, compared to institution of therapy later in childhood.
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Affiliation(s)
- Robert J Schroth
- Rady Faculty of Health Sciences, University of Manitoba, Canada; Children's Hospital Research Institute of Manitoba, Canada; Section of Pediatric Dentistry, Winnipeg Regional Health Authority, Canada; Shared Health Manitoba, Canada.
| | - Catherine Long
- Rady Faculty of Health Sciences, University of Manitoba, Canada
| | - Victor H K Lee
- Rady Faculty of Health Sciences, University of Manitoba, Canada; Children's Hospital Research Institute of Manitoba, Canada
| | | | - Cheryl Rockman-Greenberg
- Rady Faculty of Health Sciences, University of Manitoba, Canada; Children's Hospital Research Institute of Manitoba, Canada; Shared Health Manitoba, Canada
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Whyte MP, May JD, McAlister WH, Burgener K, Cortez SR, Kreienkamp R, Castro O, Verzola R, Zavala AS, McPherson CC, Gottesman GS, Ericson KL, Coburn SP, Arbelaez AM. Vitamin B 6 deficiency with normal plasma levels of pyridoxal 5'-phosphate in perinatal hypophosphatasia. Bone 2021; 150:116007. [PMID: 34000433 DOI: 10.1016/j.bone.2021.116007] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 04/29/2021] [Accepted: 05/10/2021] [Indexed: 01/29/2023]
Abstract
Pyridoxal 5'-phosphate (PLP), the principal circulating form of vitamin B6 (B6), is elevated in the plasma of individuals with hypophosphatasia (HPP). HPP is the inborn-error-of-metabolism caused by loss-of-function mutation(s) of ALPL, the gene that encodes the "tissue-nonspecific" isoenzyme of alkaline phosphatase (TNSALP). PLP accumulates extracellularly in HPP because it is a natural substrate of this cell-surface phosphomonoester phosphohydrolase. Even individuals mildly affected by HPP manifest this biochemical hallmark, which is used for diagnosis. Herein, an exclusively breast-fed newborn boy with life-threatening perinatal HPP had uniquely normal instead of markedly elevated plasma PLP levels before beginning asfotase alfa (AA) TNSALP-replacement therapy. These abnormal PLP levels were explained by B6 deficiency, confirmed by his low plasma level of 4-pyridoxic acid (PA), the B6 degradation product. His mother, a presumed carrier of one of his two ALPL missense mutations, had serum ALP activity of 50 U/L (Nl 40-130) while her plasma PLP level was 9 μg/L (Nl 5-50) and PA was 3 μg/L (Nl 3-30). Her dietary history and breast milk pyridoxal (PL) level indicated she too was B6 deficient. With B6 supplementation using a breast milk fortifier, the patient's plasma PA level corrected, while his PLP level remained in the normal range but now in keeping with AA treatment. Our experience reveals that elevated levels of PLP in the circulation in HPP require some degree of B6 sufficiency, and that anticipated increases in HPP can be negated by hypovitaminosis B6.
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Affiliation(s)
- Michael P Whyte
- Division of Pediatric Endocrinology, St. Louis Children's Hospital at Washington University School of Medicine, 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; Center for Metabolic Bone Disease and Molecular Research, Shriners Hospitals for Children - St Louis, St. Louis, MO 63110, USA.
| | - Jennifer D May
- Division of Pediatric Endocrinology, St. Louis Children's Hospital at Washington University School of Medicine, St. Louis, MO 63110, USA.
| | - William H McAlister
- Mallinckrodt Institute of Radiology, Washington University School of Medicine at St. Louis Children's Hospital, St. Louis, MO 63110, USA.
| | - Katherine Burgener
- Division of Pediatric Endocrinology, St. Louis Children's Hospital at Washington University School of Medicine, St. Louis, MO 63110, USA.
| | - Samuel R Cortez
- Division of Pediatric Endocrinology, St. Louis Children's Hospital at Washington University School of Medicine, St. Louis, MO 63110, USA.
| | - Raymond Kreienkamp
- Division of Pediatric Endocrinology, St. Louis Children's Hospital at Washington University School of Medicine, St. Louis, MO 63110, USA.
| | - Olivia Castro
- Nutritional Services, Department of Pediatrics, St. Louis Children's Hospital at Washington University School of Medicine, St. Louis, MO 63110, USA.
| | - Rachel Verzola
- Nutritional Services, Department of Pediatrics, St. Louis Children's Hospital at Washington University School of Medicine, St. Louis, MO 63110, USA.
| | - Ana Solis Zavala
- Division of Pediatric Endocrinology, St. Louis Children's Hospital at Washington University School of Medicine, St. Louis, MO 63110, USA.
| | - Christopher C McPherson
- Department of Pharmacy, St. Louis Children's Hospital at Washington University School of Medicine, St. Louis, MO 63110, USA.
| | - Gary S Gottesman
- Division of Pediatric Endocrinology, St. Louis Children's Hospital at Washington University School of Medicine, St. Louis, MO 63110, USA; 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.
| | - Ana Maria Arbelaez
- Division of Pediatric Endocrinology, St. Louis Children's Hospital at Washington University School of Medicine, St. Louis, MO 63110, USA.
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Kinoshita Y, Mohamed FF, Amadeu de Oliveira F, Narisawa S, Miyake K, Foster BL, Millán JL. Gene Therapy Using Adeno-Associated Virus Serotype 8 Encoding TNAP-D 10 Improves the Skeletal and Dentoalveolar Phenotypes in Alpl -/- Mice. J Bone Miner Res 2021; 36:1835-1849. [PMID: 34076297 PMCID: PMC8446309 DOI: 10.1002/jbmr.4382] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 05/25/2021] [Accepted: 05/28/2021] [Indexed: 12/26/2022]
Abstract
Hypophosphatasia (HPP) is caused by loss-of-function mutations in the ALPL gene that encodes tissue-nonspecific alkaline phosphatase (TNAP), whose deficiency results in the accumulation of extracellular inorganic pyrophosphate (PPi ), a potent mineralization inhibitor. Skeletal and dental hypomineralization characterizes HPP, with disease severity varying from life-threatening perinatal or infantile forms to milder forms that manifest in adulthood or only affect the dentition. Enzyme replacement therapy (ERT) using mineral-targeted recombinant TNAP (Strensiq/asfotase alfa) markedly improves the life span, skeletal phenotype, motor function, and quality of life of patients with HPP, though limitations of ERT include frequent injections due to a short elimination half-life of 2.28 days and injection site reactions. We tested the efficacy of a single intramuscular administration of adeno-associated virus 8 (AAV8) encoding TNAP-D10 to increase the life span and improve the skeletal and dentoalveolar phenotypes in TNAP knockout (Alpl-/- ) mice, a murine model for severe infantile HPP. Alpl-/- mice received 3 × 1011 vector genomes/body of AAV8-TNAP-D10 within 5 days postnatal (dpn). AAV8-TNAP-D10 elevated serum ALP activity and suppressed plasma PPi . Treatment extended life span of Alpl-/- mice, and no ectopic calcifications were observed in the kidneys, aorta, coronary arteries, or brain in the 70 dpn observational window. Treated Alpl-/- mice did not show signs of rickets, including bowing of long bones, enlargement of epiphyses, or fractures. Bone microstructure of treated Alpl-/- mice was similar to wild type, with a few persistent small cortical and trabecular defects. Histology showed no measurable osteoid accumulation but reduced bone volume fraction in treated Alpl-/- mice versus controls. Treated Alpl-/- mice featured normal molar and incisor dentoalveolar tissues, with the exceptions of slightly reduced molar enamel and alveolar bone density. Histology showed the presence of cementum and normal periodontal ligament attachment. These results support gene therapy as a promising alternative to ERT for the treatment of HPP. © 2021 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).
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Affiliation(s)
- Yuka Kinoshita
- Sanford Children's Health Research Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, USA
| | - Fatma F Mohamed
- Division of Biosciences, College of Dentistry, The Ohio State University, Columbus, OH, USA
| | - Flavia Amadeu de Oliveira
- Sanford Children's Health Research Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, USA
| | - Sonoko Narisawa
- Sanford Children's Health Research Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, USA
| | - Koichi Miyake
- Department of Biochemistry and Molecular Biology, Nippon Medical School, Tokyo, Japan
| | - Brian L Foster
- Division of Biosciences, College of Dentistry, The Ohio State University, Columbus, OH, USA
| | - José Luis Millán
- Sanford Children's Health Research Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, USA
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Okawa R, Kokomoto K, Nakano K. Dental effects of enzyme replacement therapy in case of childhood-type hypophosphatasia. BMC Oral Health 2021; 21:323. [PMID: 34176466 PMCID: PMC8237502 DOI: 10.1186/s12903-021-01673-2] [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] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Accepted: 06/11/2021] [Indexed: 12/02/2022] Open
Abstract
Background Hypophosphatasia (HPP), a skeletal disease characterized by hypomineralization of bone and teeth, is caused by an ALPL gene mutation that leads to low activity of the tissue non-specific alkaline phosphatase enzyme. Although enzyme replacement therapy (ERT) was recently introduced for affected patients, no known studies have been reported regarding its dental effects related to permanent teeth and jaw bones. In the present study, we examined the dental effects of ERT in a case of childhood-type hypophosphatasia, including panoramic radiography findings used to estimate the dental age of permanent teeth and mandibular bone density. Furthermore, the effects of that therapy on the periodontal condition of the patient were evaluated by comparing periodontal pocket depth before and after initiation. Case presentation An 11-year-1-month-old boy was referred to our clinic for consultation regarding oral management. Two primary incisors had spontaneously exfoliated at 1 year 8 months old and he had been diagnosed with childhood-type HPP at the age of 2 years 2 months. Obvious symptoms were localized in the dental region at the time of diagnosis, though later extended to other parts of the body such as bone pain. ERT was started at 11 years 7 months of age, after which bone pain disappeared, and motor functions and activities of daily living improved. We estimated dental age based on tooth development stage. The age gap between chronological and dental ages was expanded before treatment, and then showed a constant decrease after ERT initiation and finally disappeared. The index for mandibular bone density (mandibular cortical width / length from mesial buccal cusp to apex of first molar) was increased after ERT initiation. Furthermore, the periodontal condition for all teeth except those exfoliated was stable after starting therapy. Conclusions ERT resulted in improved tooth and mandibular bone mineralization, with notably good effects on teeth under formation. Acceleration of mineralization of roots associated with erupting teeth leads to stabilization of the periodontal condition. We concluded that ERT contributed to the improved dental condition seen in this patient. Supplementary Information The online version contains supplementary material available at 10.1186/s12903-021-01673-2.
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Affiliation(s)
- Rena Okawa
- Department of Pediatric Dentistry, Osaka University Graduate School of Dentistry, 1-8 Yamada-oka, Suita, Osaka, 565-0871, Japan.
| | - Kazuma Kokomoto
- Department of Pediatric Dentistry, Osaka University Graduate School of Dentistry, 1-8 Yamada-oka, Suita, Osaka, 565-0871, Japan
| | - Kazuhiko Nakano
- Department of Pediatric Dentistry, Osaka University Graduate School of Dentistry, 1-8 Yamada-oka, Suita, Osaka, 565-0871, Japan
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Pan WJ, Pradhan R, Pelto R, Seefried L. Pharmacokinetics of Asfotase Alfa in Adult Patients With Pediatric-Onset Hypophosphatasia. J Clin Pharmacol 2021; 61:1334-1343. [PMID: 33822385 PMCID: PMC8518624 DOI: 10.1002/jcph.1870] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Accepted: 04/01/2021] [Indexed: 11/24/2022]
Abstract
Hypophosphatasia is a rare metabolic disease resulting from variant(s) in the gene‐encoding tissue‐nonspecific isozyme of alkaline phosphatase. In this 13‐week, phase 2a, multicenter, randomized, open‐label, dose‐response study (ClinicalTrials.gov: NCT02797821), the pharmacokinetics of asfotase alfa, an enzyme replacement therapy approved for the treatment of hypophosphatasia, was assessed in adult patients with pediatric‐onset hypophosphatasia. In total, 27 adults were randomly assigned 1:1:1 to a single subcutaneous dose of asfotase alfa (0.5, 2.0, or 3.0 mg/kg) during week 1. From week 3 to week 9, patients received 0.5, 2.0, or 3.0 mg/kg subcutaneously 3 times per week (equivalent to 1.5, 6.0, or 9.0 mg/kg/wk, respectively). Noncompartmental analysis revealed exposure (maximum concentration in the dosing interval and area under the concentration‐time curve from time 0 to infinity) to asfotase alfa increased between single‐ and multiple‐dose administration and with increasing doses; however, extensive interindividual variability was observed in the concentration‐time profiles within each dose cohort. Median terminal elimination half‐life was ≈5 days following multiple‐dose administration, with steady state achieved by approximately day 29. Dose‐normalized exposure data indicated that asfotase alfa activity was approximately dose‐proportional within the studied dose range. Additionally, dose‐normalized exposure was comparable across body mass index categories of <25, ≥25 to <30, and ≥30 kg/m2, indicating that asfotase alfa dosing bioavailability was consistent in these patients, including those who were obese. These data, together with previously published pharmacodynamic results in this study population, support the use of asfotase alfa at the recommended dose of 6 mg/kg/wk in adults with pediatric‐onset hypophosphatasia.
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Affiliation(s)
- Wei-Jian Pan
- Alexion Pharmaceuticals, Inc., Boston, Massachusetts, USA
| | | | - Ryan Pelto
- Alexion Pharmaceuticals, Inc., Boston, Massachusetts, USA
| | - Lothar Seefried
- Orthopedic Department, University of Würzburg, Würzburg, Bavaria, Germany
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Nwafor DC, Brichacek AL, Ali A, Brown CM. Tissue-Nonspecific Alkaline Phosphatase in Central Nervous System Health and Disease: A Focus on Brain Microvascular Endothelial Cells. Int J Mol Sci 2021; 22:5257. [PMID: 34067629 PMCID: PMC8156423 DOI: 10.3390/ijms22105257] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 05/11/2021] [Accepted: 05/12/2021] [Indexed: 12/21/2022] Open
Abstract
Tissue-nonspecific alkaline phosphatase (TNAP) is an ectoenzyme bound to the plasma membranes of numerous cells via a glycosylphosphatidylinositol (GPI) moiety. TNAP's function is well-recognized from earlier studies establishing its important role in bone mineralization. TNAP is also highly expressed in cerebral microvessels; however, its function in brain cerebral microvessels is poorly understood. In recent years, few studies have begun to delineate a role for TNAP in brain microvascular endothelial cells (BMECs)-a key component of cerebral microvessels. This review summarizes important information on the role of BMEC TNAP, and its implication in health and disease. Furthermore, we discuss current models and tools that may assist researchers in elucidating the function of TNAP in BMECs.
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Affiliation(s)
- Divine C. Nwafor
- Department of Neuroscience, School of Medicine, West Virginia University Health Science Center, Morgantown, WV 26506, USA; (D.C.N.); (A.A.)
- Rockefeller Neuroscience Institute, West Virginia University, Morgantown, WV 26506, USA
| | - Allison L. Brichacek
- Department of Microbiology, Immunology, and Cell Biology, School of Medicine, West Virginia University Health Science Center, Morgantown, WV 26506, USA;
| | - Ahsan Ali
- Department of Neuroscience, School of Medicine, West Virginia University Health Science Center, Morgantown, WV 26506, USA; (D.C.N.); (A.A.)
- Rockefeller Neuroscience Institute, West Virginia University, Morgantown, WV 26506, USA
| | - Candice M. Brown
- Department of Neuroscience, School of Medicine, West Virginia University Health Science Center, Morgantown, WV 26506, USA; (D.C.N.); (A.A.)
- Rockefeller Neuroscience Institute, West Virginia University, Morgantown, WV 26506, USA
- Department of Microbiology, Immunology, and Cell Biology, School of Medicine, West Virginia University Health Science Center, Morgantown, WV 26506, USA;
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Kishnani PS, Del Angel G, Zhou S, Rush ET. Investigation of ALPL variant states and clinical outcomes: An analysis of adults and adolescents with hypophosphatasia treated with asfotase alfa. Mol Genet Metab 2021; 133:113-121. [PMID: 33814268 DOI: 10.1016/j.ymgme.2021.03.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 02/03/2021] [Accepted: 03/14/2021] [Indexed: 12/22/2022]
Abstract
BACKGROUND Hypophosphatasia (HPP), a rare metabolic disease, can be inherited in an autosomal recessive (biallelic) or an autosomal dominant (monoallelic) manner. Most of the severe, early-onset, frequently lethal HPP in infants is acquired through recessive inheritance; less severe, later-onset, typically nonlethal HPP phenotypes are acquired through either dominant or recessive inheritance. HPP's variable clinical presentation arises from >400 identified ALPL pathogenic variants with likely variable penetrance, especially with autosomal dominant inheritance. This post hoc analysis investigated the relationship between ALPL variant state (biallelic and monoallelic) and clinical outcomes with asfotase alfa in HPP. METHODS Data were pooled from two phase 2, randomized, open-label studies in adolescents and adults with HPP; one study evaluated the efficacy and safety of different doses of asfotase alfa (n = 25), and the other assessed the pharmacodynamics and safety of asfotase alfa (n = 19). Patients were grouped by ALPL variant state (biallelic or monoallelic). Available data from both studies included ALPL pathogenic variant state, Baseline characteristics, HPP-specific medical history, and Baseline TNSALP substrate levels (inorganic pyrophosphate [PPi] and pyridoxal 5'-phosphate [PLP]) concentrations). Clinical outcomes over 5 years of treatment were available from only the efficacy and safety study. RESULTS In total, 44 patients with known variant status were included in the pooled analysis (biallelic, n = 30; monoallelic, n = 14). The most common pathogenic variant was c.571G > A (p.Glu191Lys) in biallelic patients (allele frequency: 19/60) and c.1133A > T (p.Asp378Val) in monoallelic patients (allele frequency: 7/28). Median (min, max) Baseline PPi concentrations were significantly higher in patients with a biallelic vs monoallelic variant state (5.3 [2.2, 12.1] vs 4.3 [3.5, 7.4] μM; P = 0.0113), as were Baseline PLP concentrations (221.4 [62.4, 1590.0] vs 75.1 [28.8, 577.0] ng/mL; P= 0.0022). HPP-specific medical history was generally similar between biallelic and monoallelic patients in terms of incidence and type of manifestations; notable exceptions included fractures, which were more common among monoallelic patients, and delayed walking and bone deformities such as abnormally shaped chest and head and bowing of arms or legs, which were more common among biallelic patients. Data from the efficacy and safety study (n = 19) showed that median PPi and PLP concentrations were normalized over 5 years of treatment in patients with both variant states. Median % predicted distance walked on the 6-Minute Walk Test remained within the normal range for monoallelic patients over 4 years of treatment, and improved from below normal (<84%) to normal in biallelic patients. CONCLUSIONS Although patients with biallelic variants had significantly higher Baseline PPi and PLP levels than monoallelic variants, both groups generally showed similar pretreatment Baseline clinical characteristics. Treatment with asfotase alfa for up to 5 years normalized TNSALP substrate concentrations and improved functional outcomes, with no clear differences between biallelic and monoallelic variant states. This study suggests that patients with HPP have significant disease burden, regardless of ALPL variant state.
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Affiliation(s)
- Priya S Kishnani
- Department of Pediatrics, Duke University Medical Center, 2351 Erwin Road, Durham, NC, USA.
| | | | - Shanggen Zhou
- Covance, Inc., 206 Carnegie Center Dr, Princeton, NJ, USA.
| | - Eric T Rush
- Children's Mercy Hospital Kansas City, 2401 Gillham Rd, Kansas City, MO, USA; University of Missouri-Kansas City School of Medicine, Kansas City, MO, USA; University of Kansas School of Medicine, Kansas City, KS, USA.
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Hypophosphatasia: A Unique Disorder of Bone Mineralization. Int J Mol Sci 2021; 22:ijms22094303. [PMID: 33919113 PMCID: PMC8122659 DOI: 10.3390/ijms22094303] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Revised: 04/18/2021] [Accepted: 04/19/2021] [Indexed: 12/25/2022] Open
Abstract
Hypophosphatasia (HPP) is a rare genetic disease characterized by a decrease in the activity of tissue non-specific alkaline phosphatase (TNSALP). TNSALP is encoded by the ALPL gene, which is abundantly expressed in the skeleton, liver, kidney, and developing teeth. HPP exhibits high clinical variability largely due to the high allelic heterogeneity of the ALPL gene. HPP is characterized by multisystemic complications, although the most common clinical manifestations are those that occur in the skeleton, muscles, and teeth. These complications are mainly due to the accumulation of inorganic pyrophosphate (PPi) and pyridoxal-5′-phosphate (PLP). It has been observed that the prevalence of mild forms of the disease is more than 40 times the prevalence of severe forms. Patients with HPP present at least one mutation in the ALPL gene. However, it is known that there are other causes that lead to decreased alkaline phosphatase (ALP) levels without mutations in the ALPL gene. Although the phenotype can be correlated with the genotype in HPP, the prediction of the phenotype from the genotype cannot be made with complete certainty. The availability of a specific enzyme replacement therapy for HPP undoubtedly represents an advance in therapeutic strategy, especially in severe forms of the disease in pediatric patients.
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Abstract
Delineating the genetic background and the underlying pathophysiology of rare skeletal dysplasias enables a broader understanding of these disorders as well as novel perspectives regarding differential diagnosis and targeted development of therapeutic approaches. Hypophosphatasia (HPP) due to genetically determined Alkaline Phosphatase deficiency exemplifies this development. While an enzyme replacement therapy could be established for severe HPP with the prevailing bone manifestation, the clinical impact of not immediately bone-related manifestations just being successively understood. Correspondingly, the elucidation of the pathophysiology underlying renal phosphate wasting expanded our knowledge regarding phosphate metabolism and bone health and facilitated the development of an anti-FGF-23 Antibody for targeted treatment of X‑linked Hypophosphatemia (XLH). Evolutions regarding the nosology of osteogenesis imperfecta (OI) along with the identification of further causative genes also detected in the context of genetically determined osteoporosis illustrate the pathophysiologic interrelation between monogenetic bone dysplasias and multifactorial osteoporosis. While current therapeutic strategies for OI follow osteoporosis treatment, the expanding knowledge about OI forms the fundament for establishing improved treatment strategies-for both OI and osteoporosis. Similar developments are emerging regarding rare skeletal disorders like Achondroplasia, Fibrodysplasia ossificans progressive and Morbus Morquio (Mukopolysaccharidosis Type IV).
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Affiliation(s)
- Lothar Seefried
- Orthopädisches Zentrum für Muskuloskeletale Forschung, Universität Würzburg, Brettreichstr. 11, 97074, Würzburg, Deutschland.
| | - Franz Jakob
- Orthopädisches Zentrum für Muskuloskeletale Forschung, Universität Würzburg, Brettreichstr. 11, 97074, Würzburg, Deutschland
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50
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Laroche M, Couture G, Faruch M, Ruyssen-Witrand A, Porquet-Bordes V, Salles JP, Degboe Y. Hypophosphatasia: A Case of Two Patients With Spinal Cord Compression From Increase in Ligamentous Ossifications During Treatment. JBMR Plus 2021; 5:e10449. [PMID: 33869986 PMCID: PMC8046109 DOI: 10.1002/jbm4.10449] [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: 10/13/2020] [Accepted: 11/08/2020] [Indexed: 11/20/2022] Open
Abstract
Treatment with asfotase alfa has transformed the prognosis of hypophosphatasia in children and improves the bone and muscle signs in adults. The doses used in adults are the same as in children, whereas bone remodeling is different between them. We report on the cases of two patients treated with 1 mg/kg/day of asfotase alfa who developed spinal cord compression from spinal ossifications during treatment. The first patient, 50 years old, presented after 2 years of treatment with quadraparesis secondary to an increase in ossifications of the cervical vertebral ligaments. The neurological damage was resolved after laminectomy, and the patient was then treated for 18 months with doses of 80 mg per week, without recurrence of the bone and muscle signs. The second patient, 26 years old, 78 kg, developed pain and cervical stiffness with pyramidal tract irritation secondary to ossifications of the vertebral ligaments. This improved with a reduction of doses to 80 mg/week, which then, after 6 months of follow‐up, enabled maintained improvement of the bone and muscle pain that was initially obtained. To our knowledge, these are the first reported cases of increased spinal ligamentous ossifications with neurological complications. Biological monitoring in adults does not seem to enable asfotase alfa doses to be adjusted. The levels of serum alkaline phosphatase (ALP) while on the recommended treatment of 1 mg/kg/day are significantly supraphysiological (5000 to 20,000 IU) and the assays of pyrophosphate and pyridoxal phosphate are not correlated with clinical efficacy. In both of our patients, the treatment with 80 mg of asfotase alfa per week, which was proposed after the occurrence of spinal complications, seemed as effective, after a follow‐up of 18 months and 6 months, as the initial treatment for improving the bone and muscle signs, and could be provided as “attack” doses after healing of the pseudoarthroses. © 2021 American Society for Bone and Mineral Research © 2020 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)
- Michel Laroche
- Centre de Rhumatologie du Centre Hospitalo-Universitaire de Toulouse [Rheumatology Center of Toulouse University Hospital] Toulouse France
| | - Guillaume Couture
- Centre de Rhumatologie du Centre Hospitalo-Universitaire de Toulouse [Rheumatology Center of Toulouse University Hospital] Toulouse France
| | - Marie Faruch
- Service de Radiologie du Centre Hospitalo-Universitaire de Toulouse [Department of Radiology of Toulouse University Hospital] Toulouse France
| | - Adeline Ruyssen-Witrand
- Centre de Rhumatologie du Centre Hospitalo-Universitaire de Toulouse [Rheumatology Center of Toulouse University Hospital] Toulouse France
| | - Valérie Porquet-Bordes
- Endocrinologie, Maladies Osseuses, Hôpital des Enfants, Centre de Référence des Maladies Rares du Métabolisme du Calcium et Phosphate, European Reference Network on rare bone diseases, Centre Hospitalo-Universitaire de Toulouse Toulouse France
| | - Jean Pierre Salles
- Endocrinologie, Maladies Osseuses, Hôpital des Enfants, Centre de Référence des Maladies Rares du Métabolisme du Calcium et Phosphate, European Reference Network on rare bone diseases, Centre Hospitalo-Universitaire de Toulouse Toulouse France.,INSERM UMR 1043 CNRS5825, Centre de Physiopathologie de Toulouse Purpan, Centre de Physiopathology Toulouse Purpan, Université de Toulouse Toulouse France
| | - Yannick Degboe
- Centre de Rhumatologie du Centre Hospitalo-Universitaire de Toulouse [Rheumatology Center of Toulouse University Hospital] Toulouse France.,INSERM UMR 1043 CNRS5825, Centre de Physiopathologie de Toulouse Purpan, Centre de Physiopathology Toulouse Purpan, Université de Toulouse Toulouse France
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