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Calmarza P, Lapresta C, Martínez García M, Ochoa J, Sienes Bailo P, Acha Pérez J, Beltrán Audera J, González-Roca E. Musculoskeletal pain and muscular weakness as the main symptoms of adult hypophosphatasia in a Spanish cohort: clinical characterization and identification of a new ALPL gene variant. J Bone Miner Metab 2023; 41:654-665. [PMID: 37351650 DOI: 10.1007/s00774-023-01440-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: 01/04/2023] [Accepted: 05/15/2023] [Indexed: 06/24/2023]
Abstract
INTRODUCTION Hypophosphatasia (HPP) is a rare inherited disorder, caused by mutations in the alkaline phosphatase (ALPL) gene, which encodes for the tissue non-specific alkaline phosphatase (TNSALP) isoform of alkaline phosphatase (ALP). Adult HPP is one of the mild forms that presents with unspecific signs such as osteopenia, osteomalacia and muscle involvement. Our purpose was to identify and characterize possibly misdiagnosed adult HPP patients at a clinical and biochemical level. MATERIAL AND METHODS At the laboratory of Miguel Servet University Hospital we retrospectively reviewed serum ALP levels in adults over a 48-month period. The clinical records of individuals with consistently low ALP levels were reviewed to exclude secondary causes. Those with persistent hypophosphatasemia were screened for symptoms of HPP. The study participants were evaluated at biochemical and genetic levels. RESULTS We identified 705 ALP determinations (out of 384,000 processed) in 589 patients below the reference range (30 U/l). Only 21 patients with clinical signs and symptoms of HPP were selected for genetic testing. Finally, only 12 patients participated in the study, 83.3% of whom (10/12) harbored a pathogenic or likely pathogenic variant in a heterozygous state. The major symptoms of our cohort were the presence of musculoskeletal pain (100% of patients) and muscular weakness (83.3% patients). CONCLUSION Mild HPP patients presenting with diffuse symptoms such as musculoskeletal pain may be undiagnosed or misdiagnosed as osteoporosis patients by routine diagnosis. It is important to identify these individuals, to avoid inappropriate treatment with antiresorptive drugs.
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Affiliation(s)
- Pilar Calmarza
- Clinical Biochemistry Department, IIS Aragón, Miguel Servet University Hospital, Network Research Center in Cardiovascular Diseases (CIBERCV), University of Zaragoza, 50009, Zaragoza, Spain.
| | - Carlos Lapresta
- Preventive Medicine Department, Miguel Servet University Hospital, 50009, Zaragoza, Spain
| | | | - José Ochoa
- Occupational Risk Prevention Service, MAS Prevention, Zaragoza, Spain
| | - Paula Sienes Bailo
- Clinical Biochemistry Department, Miguel Servet University Hospital, 50009, Zaragoza, Spain
| | - Javier Acha Pérez
- Endocrinology Department, Miguel Servet University Hospital, 50009, Zaragoza, Spain
| | - Jesús Beltrán Audera
- Rheumatology department, Miguel Servet University Hospital, 50009, Zaragoza, Spain
| | - Eva González-Roca
- Molecular Biology Core Lab/Immunology Department, CDB. Hospital Clínic, Barcelona, Spain
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Li X, Ren N, Wang Z, Wang Y, Hu Y, Hu W, Gu J, Hong W, Zhang Z, Wang C. Clinical and Genetic Characteristics of Hypophosphatasia in Chinese Adults. Genes (Basel) 2023; 14:genes14040922. [PMID: 37107680 PMCID: PMC10137706 DOI: 10.3390/genes14040922] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Revised: 04/06/2023] [Accepted: 04/12/2023] [Indexed: 04/29/2023] Open
Abstract
Hypophosphatasia (HPP) is an inherited disease caused by ALPL mutation, resulting in decreased alkaline phosphatase (ALP) activity and damage to bone and tooth mineralization. The clinical symptoms of adult HPP are variable, making diagnosis challenging. This study aims to clarify the clinical and genetic characteristics of HPP in Chinese adults. There were 19 patients, including 1 with childhood-onset and 18 with adult-onset HPP. The median age was 62 (32-74) years and 16 female patients were involved. Common symptoms included musculoskeletal symptoms (12/19), dental problems (8/19), fractures (7/19), and fatigue (6/19). Nine patients (47.4%) were misdiagnosed with osteoporosis and six received anti-resorptive treatment. The average serum ALP level was 29.1 (14-53) U/L and 94.7% (18/19) of patients had ALP levels below 40 U/L. Genetic analysis found 14 ALPL mutations, including three novel mutations-c.511C>G (p.His171Ala), c.782C>A (p.Pro261Gln), and 1399A>G (p.Met467Val). The symptoms of two patients with compound heterozygous mutations were more severe than those with heterozygous mutations. Our study summarized the clinical characteristics of adult HPP patients in the Chinese population, expanded the spectrum of pathogenic mutations, and deepened clinicians' understanding of this neglected disease.
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Affiliation(s)
- Xiang Li
- Shanghai Clinical Research Center of Bone Disease & Department of Osteoporosis and Bone Diseases, Shanghai Sixth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai 200233, China
| | - Na Ren
- Shanghai Clinical Research Center of Bone Disease & Department of Osteoporosis and Bone Diseases, Shanghai Sixth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai 200233, China
| | - Ziyuan Wang
- Shanghai Clinical Research Center of Bone Disease & Department of Osteoporosis and Bone Diseases, Shanghai Sixth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai 200233, China
| | - Ya Wang
- Shanghai Clinical Research Center of Bone Disease & Department of Osteoporosis and Bone Diseases, Shanghai Sixth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai 200233, China
| | - Yunqiu Hu
- Shanghai Clinical Research Center of Bone Disease & Department of Osteoporosis and Bone Diseases, Shanghai Sixth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai 200233, China
| | - Weiwei Hu
- Shanghai Clinical Research Center of Bone Disease & Department of Osteoporosis and Bone Diseases, Shanghai Sixth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai 200233, China
| | - Jiemei Gu
- Shanghai Clinical Research Center of Bone Disease & Department of Osteoporosis and Bone Diseases, Shanghai Sixth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai 200233, China
| | - Wei Hong
- Department of Osteoporosis & Shanghai Key Laboratory of Clinical Geriatric Medicine, Huadong Hospital, Fudan University, Shanghai 200040, China
| | - Zhenlin Zhang
- Clinical Research Center, Shanghai Sixth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai 200233, China
| | - Chun Wang
- Shanghai Clinical Research Center of Bone Disease & Department of Osteoporosis and Bone Diseases, Shanghai Sixth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai 200233, China
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Smart G, Jensen ED, Poirier BF, Sethi S. The impact of enzyme replacement therapy on the oral health manifestations of hypophosphatasia among children: a scoping review. Eur Arch Paediatr Dent 2023:10.1007/s40368-023-00796-0. [PMID: 37036643 DOI: 10.1007/s40368-023-00796-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Accepted: 03/22/2023] [Indexed: 04/11/2023]
Abstract
PURPOSE A scoping review to describe the use of enzyme replacement therapy (ERT) in the form of asfotase alfa to decrease the severity of oral manifestations in children with hypophosphatasia (HPP). METHODS Six databases were searched using keywords and index terms related to "hypophosphatasia," "children," and "enzyme replacement therapy." Duplicates were removed and two independent reviewers screened the titles and abstracts to identify articles for full-text review. Extracted data was summarised narratively. RESULTS The systematic search identified 3548 articles, with 171 suitable for full-text review and a final 22 that met inclusion criteria. Enzyme replacement therapy generally resulted in a reduction in the presence and severity of oral manifestations of HPP. However, numerous studies failed to report specific details regarding the nature of oral health outcomes and there were reported cases of further loss of primary teeth. CONCLUSIONS The available evidence suggests that that ERT in the form of asfotase alfa for HPP in infants and young children leads to improved oral health outcomes. It is recommended that the outcomes are improved with earlier initiation of ERT. Further, well-designed clinical research is required to assess oral health improvements and decreased morbidity associated with the early loss of teeth.
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Affiliation(s)
- G Smart
- Department of Paediatric Dentistry, Women's and Children's Hospital, 72 King William Road, North Adelaide, SA, 5006, Australia.
| | - E D Jensen
- Department of Paediatric Dentistry, Women's and Children's Hospital, 72 King William Road, North Adelaide, SA, 5006, Australia
- Adelaide Dental School, The University of Adelaide, Adelaide, SA, Australia
| | - B F Poirier
- Adelaide Dental School, The University of Adelaide, Adelaide, SA, Australia
| | - S Sethi
- Adelaide Dental School, The University of Adelaide, Adelaide, SA, Australia
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Different Dental Manifestations in Sisters with the Same ALPL Gene Mutation: A Report of Two Cases. CHILDREN (BASEL, SWITZERLAND) 2022; 9:children9121850. [PMID: 36553293 PMCID: PMC9777029 DOI: 10.3390/children9121850] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Revised: 11/24/2022] [Accepted: 11/25/2022] [Indexed: 11/29/2022]
Abstract
Hypophosphatasia (HPP) is an inherited disease caused by mutation of the alkaline phosphatase (ALPL) gene in an autosomal dominant or an autosomal recessive manner. The main symptoms of HPP are bone hypomineralization and early exfoliation of the primary teeth. Some of the mutations identified in autosomal dominant families are reported to have dominant negative effects. In addition, the penetrance can vary among patients with the same variant even within the same family, resulting in various phenotypes of systemic symptoms. However, differences in dental symptoms between patients with HPP and carriers with the same ALPL variant have not been reported. Herein, we report on two sisters who had the same heterozygous ALPL variant with dominant negative effects. The older sister had bone and dental symptoms and was diagnosed with childhood HPP. In contrast, the younger sister was a carrier with no bone and dental symptoms. It can be inferred that this phenomenon was caused by the difference in penetrance. This case revealed that carriers with the ALPL mutation may have no dental symptoms characteristic of HPP. Because HPP is sometimes progressive, it is very important to carefully monitor carriers to detect the possible onset of dental and systemic symptoms.
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Glotov OS, Savostyanov KV, Nagornova TS, Chernov AN, Fedyakov MA, Raspopova AN, Krasnoukhov KN, Danilov LG, Moiseeva NV, Kalinin RS, Tsai VV, Eismont YA, Voinova VY, Vitebskaya AV, Gurkina EY, Kuzenkova LM, Sosnina IB, Pushkov AA, Zhanin IS, Zakharova EY. Clinical and Genetic Characteristics of Pediatric Patients with Hypophosphatasia in the Russian Population. Int J Mol Sci 2022; 23:ijms232112976. [PMID: 36361766 PMCID: PMC9654387 DOI: 10.3390/ijms232112976] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Revised: 10/14/2022] [Accepted: 10/17/2022] [Indexed: 11/16/2022] Open
Abstract
(1) Hypophosphatasia (HPP) is a rare inherited disease caused by mutations (pathogenic variants) in the ALPL gene which encodes tissue-nonspecific alkaline phosphatase (TNSALP). HPP is characterized by impaired bone mineral metabolism due to the low enzymatic activity of TNSALP. Knowledge about the structure of the gene and the features and functions of various ALPL gene variants, taking into account population specificity, gives an understanding of the hereditary nature of the disease, and contributes to the diagnosis, prevention, and treatment of the disease. The purpose of the study was to describe the spectrum and analyze the functional features of the ALPL gene variants, considering various HPP subtypes and clinical symptoms in Russian children. (2) From 2014−2021, the study included the blood samples obtained from 1612 patients with reduced alkaline phosphatase activity. The patients underwent an examination with an assessment of their clinical symptoms and biochemical levels of TNSALP. DNA was isolated from dried blood spots (DBSs) or blood from the patients to search for mutations in the exons of the ALPL gene using Sanger sequencing. The PCR products were sequenced using a reagent BigDye Terminator 3.1 kit (Applied Biosystems). Statistical analysis was performed using the GraphPad Prism 8.01 software. (3) The most common clinical symptoms in Russian patients with HPP and two of its variants (n = 22) were bone disorders (75%), hypomyotonia (50%), and respiratory failure (50%). The heterozygous carriage of the causal variants of the ALPL gene was detected in 225 patients. A total of 2 variants were found in 27 patients. In this group (n = 27), we identified 28 unique variants of the ALPL gene, of which 75.0% were missense, 17.9% were frameshift, 3.6% were splicing variants, and 3.6% were duplications. A total of 39.3% (11/28) of the variants were pathogenic, with two variants being probably pathogenic, and 15 variants had unknown clinical significance (VUS). Among the VUS group, 28.6% of the variants (7/28) were discovered by us for the first time. The most common variants were c.571G > A (p.Glu191Lys) and c.1171del (Arg391Valfs*12), with frequencies of 48.2% (13/28) and 11% (3/28), respectively. It was found that the frequency of nonsense variants of the ALPL gene was higher (p < 0.0001) in patients with the perinatal form compared to the infantile and childhood forms of HPP. Additionally, the number of homozygotes in patients with the perinatal form exceeded (p < 0.01) the frequencies of these genotypes in children with infantile and childhood forms of HPP. On the contrary, the frequencies of the compound-heterozygous and heterozygous genotypes were higher (p < 0.01) in patients with infantile childhood HPP than in perinatal HPP. In the perinatal form, residual TNSALP activity was lower (p < 0.0005) in comparison to the infantile and childhood (p < 0.05) forms of HPP. At the same time, patients with the heterozygous and compound-heterozygous genotypes (mainly missense variants) of the ALPL gene had greater residual activity (of the TNSALP protein) regarding those homozygous patients who were carriers of the nonsense variants (deletions and duplications) of the ALPL gene. Residual TNSALP activity was lower (p < 0.0001) in patients with pathogenic variants encoding the amino acids from the active site and the calcium and crown domains in comparison with the nonspecific region of the protein.
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Affiliation(s)
- Oleg S. Glotov
- Department of Genomic Medicine, D. O. Ott Research Institute of Obstetrics, Gynaecology and Reproductology, 199034 Saint-Petersburg, Russia
- Department of Experimental Medical Virology, Molecular Genetics and Biobanking of Pediatric Research and Clinical Center for Infectious Diseases, 197022 Saint-Petersburg, Russia
- Correspondence: (O.S.G.); (A.N.C.)
| | | | | | - Alexandr N. Chernov
- Department of Genomic Medicine, D. O. Ott Research Institute of Obstetrics, Gynaecology and Reproductology, 199034 Saint-Petersburg, Russia
- Bioenergetics Department of Life Sciences, The National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
- Department of General Pathology and Pathological Physiology, Institute of Experimental Medicine, 197376 Saint-Petersburg, Russia
- Correspondence: (O.S.G.); (A.N.C.)
| | - Mikhail A. Fedyakov
- CerbaLab Ltd., 199106 Saint-Petersburg, Russia
- City Hospital No. 40, St.-Petersburg, 9 Borisova Str., Sestrorezk, 197706 Saint-Petersburg, Russia
| | | | | | - Lavrentii G. Danilov
- CerbaLab Ltd., 199106 Saint-Petersburg, Russia
- Department of Genetics and Biotechnology, Saint-Petersburg State University, 199034 Saint-Petersburg, Russia
| | | | - Roman S. Kalinin
- Department of Genomic Medicine, D. O. Ott Research Institute of Obstetrics, Gynaecology and Reproductology, 199034 Saint-Petersburg, Russia
- Department of Experimental Medical Virology, Molecular Genetics and Biobanking of Pediatric Research and Clinical Center for Infectious Diseases, 197022 Saint-Petersburg, Russia
| | - Victoria V. Tsai
- Department of Genomic Medicine, D. O. Ott Research Institute of Obstetrics, Gynaecology and Reproductology, 199034 Saint-Petersburg, Russia
- Department of Experimental Medical Virology, Molecular Genetics and Biobanking of Pediatric Research and Clinical Center for Infectious Diseases, 197022 Saint-Petersburg, Russia
- CerbaLab Ltd., 199106 Saint-Petersburg, Russia
| | - Yuri A. Eismont
- Department of Experimental Medical Virology, Molecular Genetics and Biobanking of Pediatric Research and Clinical Center for Infectious Diseases, 197022 Saint-Petersburg, Russia
- CerbaLab Ltd., 199106 Saint-Petersburg, Russia
| | - Victoria Y. Voinova
- Veltischev Research and Clinical Institute for Pediatrics, Pirogov Russian National Research Medical University, 117997 Moscow, Russia
| | - Alisa V. Vitebskaya
- Department of Children’s Diseases of N.F. Filatov Clinical Institute for Children’s Health, I.M. Sechenov First Moscow State Medical University, 119991 Moscow, Russia
| | - Elena Y. Gurkina
- Children’s Rehabilitation Clinic Almazov National Medical Research Centre, 197341 Saint-Petersburg, Russia
| | - Ludmila M. Kuzenkova
- National Medical Research Center of Children Health, 119991 Moscow, Russia
- Department of Children’s Diseases of N.F. Filatov Clinical Institute for Children’s Health, I.M. Sechenov First Moscow State Medical University, 119991 Moscow, Russia
| | - Irina B. Sosnina
- Saint-Petersburg State Budgetary Healthcare Institution “Consulting and Diagnostic Center for Children”, 192289 Saint-Petersburg, Russia
| | | | - Ilya S. Zhanin
- National Medical Research Center of Children Health, 119991 Moscow, Russia
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Weider M, Schlagenhauf U, Seefried L. Oral health status of adult hypophosphatasia patients– a cross‐sectional study. J Clin Periodontol 2022; 49:1253-1261. [DOI: 10.1111/jcpe.13718] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Revised: 08/03/2022] [Accepted: 08/12/2022] [Indexed: 11/27/2022]
Affiliation(s)
- Margareta Weider
- Division of Periodontology University Hospital Wuerzburg Germany
| | | | - Lothar Seefried
- Clinical Trial Unit, Orthopedic Department University of Wuerzburg Germany
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Marini F, Masi L, Giusti F, Cianferotti L, Cioppi F, Marcucci G, Ciuffi S, Biver E, Toro G, Iolascon G, Iantomasi T, Brandi ML. ALPL Genotypes in Patients With Atypical Femur Fractures or Other Biochemical and Clinical Signs of Hypophosphatasia. J Clin Endocrinol Metab 2022; 107:e2087-e2094. [PMID: 34935951 DOI: 10.1210/clinem/dgab914] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Indexed: 11/19/2022]
Abstract
CONTEXT Hypophosphatasia (HPP) is a rare metabolic disorder caused by deficiency of alkaline phosphatase (ALP) enzyme activity, leading to defective mineralization, due to pathogenic variants of the ALPL gene, encoding the tissue nonspecific alkaline phosphatase (TNSALP) enzyme. Inheritance can be autosomal recessive or autosomal dominant. An abnormal ALPL genetic test enables accurate diagnosis, avoiding the administration of contraindicated antiresorptive drugs that, in patients with HPP, substantially increase the risk of atypical femur fractures (AFFs) and worsen the fracture healing process that is usually already compromised in these patients. OBJECTIVE Performing ALPL genetic testing to identify rare variants in suspected adult patients with HPP. Comparing frequencies of ALPL common variants in individuals with biochemical and/or clinical signs suggestive of adult HPP and non-HPP controls, and among different clinical subgroups of patients with a clinical suspicion of adult HPP. METHODS Patients with suspected adult HPP were retrospectively selected for the genetic testing of the ALPL gene. Patients included were from 3 main European Bone Units (Florence, Naples, and Geneva); 106 patients with biochemical and/or clinical signs suggestive of a mild form of HPP were included. RESULTS Genetic testing led to the identification of a heterozygote rare variant in 2.8% of cases who were initially referred as suspected osteoporosis. The analysis of frequencies of ALPL common variants showed a high prevalence (30.8%) of homozygosity in subjects who developed an AFF, in association with normal serum total ALP activity. CONCLUSION The results suggest homozygosity of common ALPL variants as a possible genetic mark of risk for these fractures.
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Affiliation(s)
- Francesca Marini
- Department of Experimental and Clinical Biomedical Sciences, University of Florence, Florence, Italy
- F.I.R.M.O. Italian Foundation for the Research on Bone Diseases, Florence, Italy
| | - Laura Masi
- University Hospital of Florence, Azienda Ospedaliero-Universitaria Careggi (AOUC), Florence, Italy
| | - Francesca Giusti
- Department of Experimental and Clinical Biomedical Sciences, University of Florence, Florence, Italy
| | - Luisella Cianferotti
- Department of Experimental and Clinical Biomedical Sciences, University of Florence, Florence, Italy
- University Hospital of Florence, Azienda Ospedaliero-Universitaria Careggi (AOUC), Florence, Italy
| | - Federica Cioppi
- University Hospital of Florence, Azienda Ospedaliero-Universitaria Careggi (AOUC), Florence, Italy
| | - Gemma Marcucci
- Department of Experimental and Clinical Biomedical Sciences, University of Florence, Florence, Italy
- University Hospital of Florence, Azienda Ospedaliero-Universitaria Careggi (AOUC), Florence, Italy
| | - Simone Ciuffi
- Department of Experimental and Clinical Biomedical Sciences, University of Florence, Florence, Italy
| | - Emmanuel Biver
- Division of Bone Diseases, Geneva University Hospitals and Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Giuseppe Toro
- Department of Medical and Surgical Specialties and Dentistry, University of Campania "Luigi Vanvitelli", Naples, Italy
| | - Giovanni Iolascon
- Department of Medical and Surgical Specialties and Dentistry, University of Campania "Luigi Vanvitelli", Naples, Italy
| | - Teresa Iantomasi
- Department of Experimental and Clinical Biomedical Sciences, University of Florence, Florence, Italy
| | - Maria Luisa Brandi
- F.I.R.M.O. Italian Foundation for the Research on Bone Diseases, Florence, Italy
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Schmidt T, Schmidt C, Amling M, Kramer J, Barvencik F. Prevalence of low alkaline phosphatase activity in laboratory assessment: Is hypophosphatasia an underdiagnosed disease? Orphanet J Rare Dis 2021; 16:452. [PMID: 34711245 PMCID: PMC8555173 DOI: 10.1186/s13023-021-02084-w] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Accepted: 10/10/2021] [Indexed: 12/28/2022] Open
Abstract
Background Tissue-nonspecific alkaline phosphatase (TNSALP) encoded by the ALPL gene is of particular importance for bone mineralization. Mutation in the ALPL gene can lead to persistent low ALP activity resulting in the rare disease Hypophosphatasia (HPP) that is characterized by disturbed bone and dental mineralization. While severe forms are extremely rare with an estimated prevalence of 1/100.000, recent studies suggest that moderate form caused by heterozygous mutations are much more frequent with an estimated prevalence of 1/508. The purpose of this study was to estimate the prevalence of low AP levels in the population based on laboratory measurements. Methods In this study, the prevalence of low AP activity and elevated pyridoxal-5-phosphate (PLP) levels was analyzed in 6.918.126 measurements from 2011 to 2016 at a single laboratory in northern Germany. Only laboratory values of subjects older than 18 years of age were included. Only the first measurement was included, all repeated values were excluded. Results In total, 8.46% of the measurements of a total of 6.918.126 values showed a value < 30 U/L. 0.59% of the subjects with an ALP activity below 30 U/L had an additional PLP measurement. Here, 6.09% showed elevated pyridoxal-5-phosphate (PLP) levels. This suggest that 0.52% (1:194) of subjects show laboratory signs of HPP. Conclusion These data support the genetic estimation that the prevalence of moderate forms of HPP may be significantly higher than expected. Based on these data, we recommend automatically measurement of PLP in the case of low ALP activity and a notification to the ordering physician that HPP should be included in the differential diagnosis and further exploration is recommended.
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Affiliation(s)
- Tobias Schmidt
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestr. 59, 22529, Hamburg, Germany
| | - Constantin Schmidt
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestr. 59, 22529, Hamburg, Germany
| | - Michael Amling
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestr. 59, 22529, Hamburg, Germany
| | - Jan Kramer
- LADR Laboratory Group Dr. Kramer and Colleagues, Geesthacht, Germany
| | - Florian Barvencik
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestr. 59, 22529, Hamburg, Germany.
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Kato M, Michigami T, Tachikawa K, Kato M, Yabe I, Shimizu T, Asaka T, Kitagawa Y, Atsumi T. Novel mutation in the ALPL gene with a dominant negative effect in a Japanese family. J Bone Miner Metab 2021; 39:804-809. [PMID: 33821301 DOI: 10.1007/s00774-021-01219-0] [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: 10/23/2020] [Accepted: 02/25/2021] [Indexed: 10/21/2022]
Abstract
INTRODUCTION Hypophosphatasia (HPP) is caused by mutations in the ALPL gene encoding tissue nonspecific alkaline phosphatase (TNSALP) and inherited in either an autosomal recessive or autosomal dominant manner. It is characterized clinically by defective mineralization of bone, dental problems, and low serum ALP levels. In the current report, we demonstrate a novel mutation in the ALPL gene (c.244G > A p.Gly82Arg) in a Japanese family with low serum ALP levels. MATERIALS AND METHODS The ALPL gene analysis using hybridization capture-based next-generation sequencing was performed. The expression plasmids of the wild type and mutated TNSALP were introduced into COS-7 cells. The enzymatic activity of ALP in the cell lysates was measured using p-nitrophenylphosphate as a substrate. RESULTS TNSALP with the novel ALPL mutation (c.244G > A p.Gly82Arg) completely lost its enzymatic activity and suppressed that of wild-type TNSALP, corroborating its dominant negative effect. The diagnosis of autosomal dominant HPP was confirmed in three members of the family. CONCLUSION Our approach would help to avoid the inappropriate use of bone resorption inhibitors for currently mis- or under-diagnosed HPP, given that the presence of further, yet undetected mutations of the ALPL gene are plausible.
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Affiliation(s)
- Masaru Kato
- Department of Rheumatology, Endocrinology and Nephrology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, N15W7, Kita-Ku, Sapporo, 060-8638, Japan.
| | - Toshimi Michigami
- Department of Bone and Mineral Research, Research Institute, Osaka Women's and Children's Hospital, Osaka Prefectural Hospital Organization, Osaka, Japan
| | - Kanako Tachikawa
- Department of Bone and Mineral Research, Research Institute, Osaka Women's and Children's Hospital, Osaka Prefectural Hospital Organization, Osaka, Japan
| | - Momoko Kato
- The Division of Clinical Genetics, Hokkaido University Hospital, Sapporo, Japan
| | - Ichiro Yabe
- The Division of Clinical Genetics, Hokkaido University Hospital, Sapporo, Japan
| | - Tomohiro Shimizu
- Department of Orthopedic Surgery, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Takuya Asaka
- Oral Diagnosis and Medicine, Hokkaido University, Sapporo, Japan
| | | | - Tatsuya Atsumi
- Department of Rheumatology, Endocrinology and Nephrology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, N15W7, Kita-Ku, Sapporo, 060-8638, Japan
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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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11
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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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12
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Kramer K, Chavez MB, Tran AT, Farah F, Tan MH, Kolli TN, Dos Santos EJL, Wimer HF, Millán JL, Suva LJ, Gaddy D, Foster BL. Dental defects in the primary dentition associated with hypophosphatasia from biallelic ALPL mutations. Bone 2021; 143:115732. [PMID: 33160095 PMCID: PMC7769999 DOI: 10.1016/j.bone.2020.115732] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Revised: 10/29/2020] [Accepted: 11/02/2020] [Indexed: 12/12/2022]
Abstract
ALPL encodes tissue-nonspecific alkaline phosphatase (TNAP), an enzyme expressed in bone, teeth, liver, and kidney. ALPL loss-of-function mutations cause hypophosphatasia (HPP), an inborn error-of-metabolism that produces skeletal and dental mineralization defects. Case reports describe widely varying dental phenotypes, making it unclear how HPP comparatively affects the three unique dental mineralized tissues: enamel, dentin, and cementum. We hypothesized that HPP affected all dental mineralized tissues and aimed to establish quantitative measurements of dental tissues in a subject with HPP. The female proband was diagnosed with HPP during childhood based on reduced alkaline phosphatase activity (ALP), mild rachitic skeletal effects, and premature primary tooth loss. The diagnosis was subsequently confirmed genetically by the presence of compound heterozygous ALPL mutations (exon 5: c.346G>A, p.A116T; exon 10: c.1077C>G, p.I359M). Dental defects in 8 prematurely exfoliated primary teeth were analyzed by high resolution micro-computed tomography (micro-CT) and histology. Similarities to the Alpl-/- mouse model of HPP were identified by additional analyses of murine dentoalveolar tissues. Primary teeth from the proband exhibited substantial remaining root structure compared to healthy control teeth. Enamel and dentin densities were not adversely affected in HPP vs. control teeth. However, analysis of discrete dentin regions revealed an approximate 10% reduction in the density of outer mantle dentin of HPP vs. control teeth. All 4 incisors and the molar lacked acellular cementum by micro-CT and histology, but surprisingly, 2 of 3 prematurely exfoliated canines exhibited apparently normal acellular cementum. Based on dentin findings in the proband's teeth, we examined dentoalveolar tissues in a mouse model of HPP, revealing that the delayed initiation of mineralization in the incisor mantle dentin was associated with a broader lack of circumpulpal dentin mineralization. This study describes a quantitative approach to measure effects of HPP on dental tissues. This approach has uncovered a previously unrecognized novel mantle dentin defect in HPP, as well as a surprising and variable cementum phenotype within the teeth from the same HPP subject.
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Affiliation(s)
- K Kramer
- Division of Orthodontics, College of Dentistry, The Ohio State University, Columbus, OH, USA
| | - M B Chavez
- Division of Biosciences, College of Dentistry, The Ohio State University, Columbus, OH, USA
| | - A T Tran
- Division of Biosciences, College of Dentistry, The Ohio State University, Columbus, OH, USA
| | - F Farah
- Division of Biosciences, College of Dentistry, The Ohio State University, Columbus, OH, USA
| | - M H Tan
- Division of Biosciences, College of Dentistry, The Ohio State University, Columbus, OH, USA
| | - T N Kolli
- Division of Biosciences, College of Dentistry, The Ohio State University, Columbus, OH, USA
| | - E J Lira Dos Santos
- Division of Biosciences, College of Dentistry, The Ohio State University, Columbus, OH, USA; Department of Prosthodontics and Periodontics, Division of Periodontics, Piracicaba Dental School, University of Campinas-UNICAMP, Piracicaba, SP, Brazil
| | - H F Wimer
- Department of Vertebrate Zoology, National Museum of Natural History, Smithsonian Institution, Washington, DC, USA; National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
| | - J L Millán
- Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, USA
| | - L J Suva
- Department of Veterinary Physiology and Pharmacology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX, USA
| | - D Gaddy
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX, USA
| | - B L Foster
- Division of Biosciences, College of Dentistry, The Ohio State University, Columbus, OH, USA.
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TNAP as a New Player in Chronic Inflammatory Conditions and Metabolism. Int J Mol Sci 2021; 22:ijms22020919. [PMID: 33477631 PMCID: PMC7831495 DOI: 10.3390/ijms22020919] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 01/14/2021] [Accepted: 01/14/2021] [Indexed: 12/19/2022] Open
Abstract
This review summarizes important information on the ectoenzyme tissue-nonspecific alkaline phosphatase (TNAP) and gives a brief insight into the symptoms, diagnostics, and treatment of the rare disease Hypophosphatasia (HPP), which is resulting from mutations in the TNAP encoding ALPL gene. We emphasize the role of TNAP beyond its well-known contribution to mineralization processes. Therefore, above all, the impact of the enzyme on central molecular processes in the nervous system and on inflammation is presented here.
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Martins L, Dos Santos EL, de Almeida AB, Machado RA, Lyrio AM, Foster BL, Kantovitz KR, Coletta RD, Nociti FH. A novel de novo heterozygous ALPL nonsense mutation associated with adult hypophosphatasia. Osteoporos Int 2020; 31:2251-2257. [PMID: 32572521 PMCID: PMC8214176 DOI: 10.1007/s00198-020-05490-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Accepted: 06/03/2020] [Indexed: 12/20/2022]
Abstract
UNLABELLED Using genetic, clinical, biochemical, and radiographic assessment and bioinformatic approaches, we present an unusual case of adult HPP caused by a novel de novo heterozygous nonsense mutation in the alkaline phosphatase (ALPL). INTRODUCTION Hypophosphatasia (HPP) is caused by genetic alterations of the ALPL gene, encoding the tissue-nonspecific isozyme of alkaline phosphatase (TNSALP). Here, the purpose was to perform clinical and molecular investigation in a 36-year-old Caucasian woman suspected to present adult HPP. METHODS Medical and dental histories were obtained for the proposita and family members, including biochemical, radiographic, and dental assessments. ALPL mutational analysis was performed by the Sanger sequencing method, and the functional impact prediction of the identified mutations was assessed by bioinformatic methods. RESULTS We identified a novel heterozygous nonsense mutation in the ALPL gene (NM_000478.6:c.768G>A; W[TGG]>*[TGA]) associated with spontaneous vertebral fracture, severe back pain, musculoskeletal pain, low bone density, and short-rooted permanent teeth loss. Functional prediction analysis revealed that the Trp256Ter mutation led to a complete loss of TNSALP crown domain and extensive loss of other functional domains (calcium-binding domain, active site vicinity, and zinc-binding site) and over 60% loss of homodimer interface residues, suggesting that the mutant TNSALP molecules are nonfunctional and form unstable homodimers. Genotyping of the ALPL in the proposita's parents, sister, and niece revealed that in this case, HPP occurred due to a de novo mutation. CONCLUSION The present study describes a novel genotype-phenotype and structure-function relationship for HPP, contributing to a better molecular comprehension of HPP etiology and pathophysiology.
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Affiliation(s)
- L Martins
- Department of Prosthodontics and Periodontics, Division of Periodontics, Piracicaba Dental School, State University of Campinas - UNICAMP, Av. Limeira, 901, Piracicaba, SP, 13414-903, Brazil
| | - E L Dos Santos
- Department of Prosthodontics and Periodontics, Division of Periodontics, Piracicaba Dental School, State University of Campinas - UNICAMP, Av. Limeira, 901, Piracicaba, SP, 13414-903, Brazil
- Division of Biosciences, College of Dentistry, The Ohio State University, Columbus, OH, USA
| | - A B de Almeida
- Department of Prosthodontics and Periodontics, Division of Periodontics, Piracicaba Dental School, State University of Campinas - UNICAMP, Av. Limeira, 901, Piracicaba, SP, 13414-903, Brazil
| | - R A Machado
- Department of Oral Diagnosis, Piracicaba Dental School, State University of Campinas - UNICAMP, Piracicaba, SP, Brazil
- Hospital for Rehabilitation of Craniofacial Anomalies, University of São Paulo (HRAC/USP), Bauru, SP, Brazil
| | - A M Lyrio
- Pontifical Catholic University of Campinas, Campinas, SP, Brazil
| | - B L Foster
- Division of Biosciences, College of Dentistry, The Ohio State University, Columbus, OH, USA
| | - K R Kantovitz
- Department of Dental Materials, São Leopoldo Research Center, Campinas, SP, Brazil
| | - R D Coletta
- Department of Oral Diagnosis, Piracicaba Dental School, State University of Campinas - UNICAMP, Piracicaba, SP, Brazil
| | - F H Nociti
- Department of Prosthodontics and Periodontics, Division of Periodontics, Piracicaba Dental School, State University of Campinas - UNICAMP, Av. Limeira, 901, Piracicaba, SP, 13414-903, Brazil.
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Mornet E, Taillandier A, Domingues C, Dufour A, Benaloun E, Lavaud N, Wallon F, Rousseau N, Charle C, Guberto M, Muti C, Simon-Bouy B. Hypophosphatasia: a genetic-based nosology and new insights in genotype-phenotype correlation. Eur J Hum Genet 2020; 29:289-299. [PMID: 32973344 DOI: 10.1038/s41431-020-00732-6] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Revised: 09/08/2020] [Accepted: 09/15/2020] [Indexed: 11/09/2022] Open
Abstract
Hypophosphatasia (HPP) is caused by pathogenic variants in the ALPL gene. There is a large continuum in the severity, ranging from a lethal perinatal form to dental issues. We analyzed a cohort of 424 HPP patients from European geographic origin or ancestry. Using 3D modeling and results of functional tests we classified ALPL pathogenic variants according to their dominant negative effect (DNE) and their severity. The cohort was described by the genotypes resulting from alleles s (severe recessive), Sd (severe dominant), and m (moderate). Many recurrent variants showed a regional anchor pointing out founder effects rather than multiple mutational events. Homozygosity was an aggravating factor of the severity and moderate alleles were rare both in number and frequency. Pathogenic variants with DNE were found in both recessive and dominant HPP. Sixty percent of the adults tested were heterozygous for a variant showing no DNE, suggesting another mechanism of dominance like haploinsufficiency. Adults with dominant HPP without DNE were found statistically less severely affected than adults with DNE variants. Adults with dominant HPP without DNE represent a new clinical entity mostly diagnosed from 2010s, characterized by nonspecific signs of HPP and low alkaline phosphatase, and for which a high prevalence is expected. In conclusion, the genetic composition of our cohort suggests a nosology with 3 clinical forms: severe HPP is recessive and rare, moderate HPP is recessive or dominant and more common, and mild HPP, characterized by low alkaline phosphatase and unspecific clinical signs, is dominantly inherited and very common.
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Affiliation(s)
- Etienne Mornet
- Unité de Génétique Constitutionnelle, Service de Biologie, Centre Hospitalier de Versailles, 78150, Le Chesnay, France.
| | - Agnès Taillandier
- Unité de Génétique Constitutionnelle, Service de Biologie, Centre Hospitalier de Versailles, 78150, Le Chesnay, France
| | - Christelle Domingues
- Unité de Génétique Constitutionnelle, Service de Biologie, Centre Hospitalier de Versailles, 78150, Le Chesnay, France
| | - Annika Dufour
- Unité de Génétique Constitutionnelle, Service de Biologie, Centre Hospitalier de Versailles, 78150, Le Chesnay, France
| | - Emmanuelle Benaloun
- Unité de Génétique Constitutionnelle, Service de Biologie, Centre Hospitalier de Versailles, 78150, Le Chesnay, France
| | - Nicole Lavaud
- Unité de Génétique Constitutionnelle, Service de Biologie, Centre Hospitalier de Versailles, 78150, Le Chesnay, France
| | - Fabienne Wallon
- Unité de Génétique Constitutionnelle, Service de Biologie, Centre Hospitalier de Versailles, 78150, Le Chesnay, France
| | - Nathalie Rousseau
- Unité de Génétique Constitutionnelle, Service de Biologie, Centre Hospitalier de Versailles, 78150, Le Chesnay, France
| | - Carole Charle
- Unité de Génétique Constitutionnelle, Service de Biologie, Centre Hospitalier de Versailles, 78150, Le Chesnay, France
| | - Mihelaiti Guberto
- Unité de Génétique Constitutionnelle, Service de Biologie, Centre Hospitalier de Versailles, 78150, Le Chesnay, France
| | - Christine Muti
- Unité de Génétique Constitutionnelle, Service de Biologie, Centre Hospitalier de Versailles, 78150, Le Chesnay, France
| | - Brigitte Simon-Bouy
- Unité de Génétique Constitutionnelle, Service de Biologie, Centre Hospitalier de Versailles, 78150, Le Chesnay, France
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Investigation of alpl expression and Tnap-activity in zebrafish implies conserved functions during skeletal and neuronal development. Sci Rep 2020; 10:13321. [PMID: 32770041 PMCID: PMC7414108 DOI: 10.1038/s41598-020-70152-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Accepted: 07/21/2020] [Indexed: 12/23/2022] Open
Abstract
Hypophosphatasia (HPP) is a rare genetic disease with diverse symptoms and a heterogeneous severity of onset with underlying mutations in the ALPL gene encoding the ectoenzyme Tissue-nonspecific alkaline phosphatase (TNAP). Considering the establishment of zebrafish (Danio rerio) as a new model organism for HPP, the aim of the study was the spatial and temporal analysis of alpl expression in embryos and adult brains. Additionally, we determined functional consequences of Tnap inhibition on neural and skeletal development in zebrafish. We show that expression of alpl is present during embryonic stages and in adult neuronal tissues. Analyses of enzyme function reveal zones of pronounced Tnap-activity within the telencephalon and the mesencephalon. Treatment of zebrafish embryos with chemical Tnap inhibitors followed by axonal and cartilage/mineralized tissue staining imply functional consequences of Tnap deficiency on neuronal and skeletal development. Based on the results from neuronal and skeletal tissue analyses, which demonstrate an evolutionary conserved role of this enzyme, we consider zebrafish as a promising species for modeling HPP in order to discover new potential therapy strategies in the long-term.
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Tilden DR, Sheehan JH, Newman JH, Meiler J, Capra JA, Ramirez A, Simmons J, Dahir K. Phenotypic Profiling in Subjects Heterozygous for 1 of 2 Rare Variants in the Hypophosphatasia Gene ( ALPL). J Endocr Soc 2020; 4:bvaa084. [PMID: 32803091 PMCID: PMC7417882 DOI: 10.1210/jendso/bvaa084] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Accepted: 06/22/2020] [Indexed: 11/19/2022] Open
Abstract
Context Hypophosphatasia (HPP) is a syndrome marked by low serum alkaline phosphatase (AlkP) activity as well as musculoskeletal and/or dental disease. While the majority of subjects with HPP carry a pathogenic variant in the ALPL gene or its regulatory regions, individual pathogenic variants are often not tightly correlated with clinical symptomatology. We sought to better understand the genotype/phenotype correlation in HPP by examining the clinical and biochemical data of 37 subjects with 2 rare variants in ALPL. Methods Through BioVU, a DNA biobank that pairs individuals’ genetic information with their de-identified medical records, we identified subjects with 2 rare variants with distinct reported clinical phenotypes (p.D294A and p.T273M). We then performed a manual review of these subjects’ de-identified medical records along with computational modeling of protein structure to construct a genetic, biochemical and clinical phenotype for each subject and variant. Results Twenty subjects with the p.D294A variant and 17 with the p.T273M variant had sufficient data for analysis. Among subjects in our cohort with the p.D294A variant, 6 (30.0%) had both clinical bone disease and serum AlkP activity below 40 IU/L while 4 subjects (23.5%) with the p.T273M variant met the same criteria despite the distinct clinical phenotypes of these variants. Conclusions Given the loose genotype/phenotype correlation in HPP seen in our cohort, clinical context is crucial for the interpretation of genetic test results to guide clinical care in this population. Otherwise, over- or under-diagnosis may occur, resulting in misidentification of those who may benefit from additional screening and perhaps pharmacologic intervention.
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Affiliation(s)
- Daniel R Tilden
- Division of Endocrinology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee.,Ian M. Burr Division of Pediatric Endocrinology, Department of Pediatrics, Monroe Carroll Jr. Children's Hospital at Vanderbilt, Nashville, Tennessee
| | - Jonathan H Sheehan
- Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri
| | - John H Newman
- Division of Allergy, Pulmonary and Critical Care Medicine, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Jens Meiler
- Center for Structural Biology, Vanderbilt University Medical Center Nashville, TN.,Department of Chemistry, Vanderbilt University Medical Center, Nashville, Tennessee.,Department of Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee
| | - John A Capra
- Center for Structural Biology, Vanderbilt University Medical Center Nashville, TN.,Department of Chemistry, Vanderbilt University Medical Center, Nashville, Tennessee.,Department of Biological Sciences and Biomedical Informatics, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Andrea Ramirez
- Division of Endocrinology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Jill Simmons
- Ian M. Burr Division of Pediatric Endocrinology, Department of Pediatrics, Monroe Carroll Jr. Children's Hospital at Vanderbilt, Nashville, Tennessee
| | - Kathryn Dahir
- Division of Endocrinology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
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del Angel G, Reynders J, Negron C, Steinbrecher T, Mornet E. Large-scale in vitro functional testing and novel variant scoring via protein modeling provide insights into alkaline phosphatase activity in hypophosphatasia. Hum Mutat 2020; 41:1250-1262. [PMID: 32160374 PMCID: PMC7317754 DOI: 10.1002/humu.24010] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Revised: 02/05/2020] [Accepted: 03/04/2020] [Indexed: 01/20/2023]
Abstract
Hypophosphatasia (HPP) is a rare metabolic disorder characterized by low tissue‐nonspecific alkaline phosphatase (TNSALP) typically caused by ALPL gene mutations. HPP is heterogeneous, with clinical presentation correlating with residual TNSALP activity and/or dominant‐negative effects (DNE). We measured residual activity and DNE for 155 ALPL variants by transient transfection and TNSALP enzymatic activity measurement. Ninety variants showed low residual activity and 24 showed DNE. These results encompass all missense variants with carrier frequencies above 1/25,000 from the Genome Aggregation Database. We used resulting data as a reference to develop a new computational algorithm that scores ALPL missense variants and predicts high/low TNSALP enzymatic activity. Our approach measures the effects of amino acid changes on TNSALP dimer stability with a physics‐based implicit solvent energy model. We predict mutation deleteriousness with high specificity, achieving a true‐positive rate of 0.63 with false‐positive rate of 0, with an area under receiver operating curve (AUC) of 0.9, better than all in silico predictors tested. Combining this algorithm with other in silico approaches can further increase performance, reaching an AUC of 0.94. This study expands our understanding of HPP heterogeneity and genotype/phenotype relationships with the aim of improving clinical ALPL variant interpretation.
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Affiliation(s)
- Guillermo del Angel
- Data Sciences, Genomics, and BioinformaticsAlexion Pharmaceuticals, Inc.BostonMassachusetts
| | - John Reynders
- Data Sciences, Genomics, and BioinformaticsAlexion Pharmaceuticals, Inc.BostonMassachusetts
| | | | | | - Etienne Mornet
- Laboratoire de Génétique Constitutionnelle Prénatale et PostnataleCentre Hospitalier de VersaillesLe ChesnayFrance
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Michigami T, Tachikawa K, Yamazaki M, Kawai M, Kubota T, Ozono K. Hypophosphatasia in Japan: ALPL Mutation Analysis in 98 Unrelated Patients. Calcif Tissue Int 2020; 106:221-231. [PMID: 31707452 DOI: 10.1007/s00223-019-00626-w] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Accepted: 10/24/2019] [Indexed: 12/19/2022]
Abstract
Hypophosphatasia (HPP) is highly variable in clinical expression and is generally classified into six subtypes. Although it would be beneficial to be able to predict the clinical course from the ALPL genotype, studies on this issue are limited. Here, we aimed to clarify the features of Japanese HPP and the relationships between genotype and clinical manifestations. We analyzed 98 unrelated Japanese patients to investigate the percentage of each clinical form, frequently detected mutations, and the relationship between the genotype and phenotype. Some of the identified mutants were characterized by transfection experiments. Perinatal severe form was the most frequent (45.9%), followed by perinatal benign form (22.4%). Among the 196 alleles, p.Leu520ArgfsX86 (c.1559delT) was detected in 89 alleles, and p.Phe327Leu (c.979T>C) was identified in 23 alleles. All of the homozygotes for p.Leu520ArgfsX86 were classified into perinatal severe form, and patients carrying p.Phe327Leu in one of the alleles were classified into perinatal benign or odonto HPP. Twenty of the 22 patients with perinatal benign HPP were compound heterozygous for p.Phe327Leu and another mutation. Most patients with odonto HPP were found to be monoallelic heterozygotes for dominant-negative mutations or compound heterozygotes with mutants having residual activity. The high prevalence of p.Leu520ArgfsX86 and p.Phe327Leu mutations might underlie the high rate of perinatal severe and perinatal benign forms, respectively, in Japanese HPP. Although ALPL genotyping would be beneficial for predicting the clinical course to an extent, the observed phenotypical variability among patients sharing the same genotypes suggests the presence of modifiers.
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Affiliation(s)
- Toshimi Michigami
- Department of Bone and Mineral Research, Research Institute, Osaka Women's and Children's Hospital, Osaka Prefectural Hospital Organization, 840 Murodo-cho, Izumi, 594-1101, Osaka, Japan.
| | - Kanako Tachikawa
- Department of Bone and Mineral Research, Research Institute, Osaka Women's and Children's Hospital, Osaka Prefectural Hospital Organization, 840 Murodo-cho, Izumi, 594-1101, Osaka, Japan
| | - Miwa Yamazaki
- Department of Bone and Mineral Research, Research Institute, Osaka Women's and Children's Hospital, Osaka Prefectural Hospital Organization, 840 Murodo-cho, Izumi, 594-1101, Osaka, Japan
| | - Masanobu Kawai
- Department of Bone and Mineral Research, Research Institute, Osaka Women's and Children's Hospital, Osaka Prefectural Hospital Organization, 840 Murodo-cho, Izumi, 594-1101, Osaka, Japan
| | - Takuo Kubota
- Department of Pediatrics, Osaka University Graduate School of Medicine, Suita, 565-0871, Osaka, Japan
| | - Keiichi Ozono
- Department of Pediatrics, Osaka University Graduate School of Medicine, Suita, 565-0871, Osaka, Japan
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Hypophosphatasie – eine klinisch und genetisch variable Erkrankung. MED GENET-BERLIN 2019. [DOI: 10.1007/s11825-019-00271-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Zusammenfassung
Die Hypophosphatasie (HPP) ist eine erbliche metabolische Multisystemerkrankung, deren klinische Hauptcharakteristika Mineralisierungsstörungen von Knochen und Zähnen sowie Muskel- und Gelenkschmerzen sind. Die klinische Symptomatik ist vom Erkrankungsalter abhängig und gestaltet sich sowohl interindividuell als auch intrafamiliär sehr variabel. Es werden sechs Unterformen der HPP abgegrenzt, wobei die Übergänge fließend sind. Sie reichen von der schweren perinatalen Form, die früher aufgrund fehlender Skelettmineralisierung meist tödlich war, bis hin zur adulten Form mit typischen Symptomen wie Frakturheilungsstörungen oder Stressfrakturen. Unspezifische Symptome wie Muskelschmerzen und -schwäche, Migräne oder Depressionen können ebenfalls Teil der HPP sein. Während schwere Formen mit einer Prävalenz zwischen 1/100.000 und 1/300.000 selten sind, kommen milde Formen der HPP deutlich häufiger vor. Perinatale und frühkindliche Formen sind meist autosomal-rezessiv vererbt, hingegen werden später auftretende Formen autosomal-rezessiv oder -dominant vererbt. Ursache der HPP ist eine reduzierte oder fehlende Aktivität der gewebeunspezifischen alkalischen Phosphatase (AP), welche durch das ALPL-Gen kodiert wird. Laborchemisch lassen sich im Serum eine alters- und geschlechtsspezifisch erniedrigte AP-Aktivität und eine konsekutive Erhöhung der AP-Substrate, z. B. des Pyridoxal-5-Phosphats (PLP), feststellen. Seit der Erstbeschreibung der Erkrankung 1948 haben sich die Diagnostik und Therapie der HPP dramatisch verbessert. Vor 4 Jahren ist eine Enzymersatztherapie mit Asfotase alfa (Strensiq®) für schwer betroffene HPP-Patienten mit Beginn der Erkrankung vor dem 18. Lebensjahr zugelassen worden. Dieser Artikel gibt einen Überblick über das breite klinische Spektrum der HPP, pathophysiologische Hintergründe, die laborchemische und molekulargenetische Diagnostik sowie gegenwärtige Therapieoptionen und deren Behandlungsindikationen.
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Mao X, Liu S, Lin Y, Chen Z, Shao Y, Yu Q, Liu H, Lu Z, Sheng H, Lu X, Huang Y, Liu L, Zeng C. Two novel mutations in the ALPL gene of unrelated Chinese children with Hypophosphatasia: case reports and literature review. BMC Pediatr 2019; 19:456. [PMID: 31760938 PMCID: PMC6876108 DOI: 10.1186/s12887-019-1800-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Accepted: 10/24/2019] [Indexed: 12/19/2022] Open
Abstract
OBJECTIVE Hypophosphatasia (HPP) is an inherited disorder of defective skeletal mineralization caused by mutations in the ALPL gene that encodes the Tissue Non-specific Alkaline Phosphatase (TNSALP). It is subdivided into six forms depending on the age of onset: perinatal lethal, prenatal benign, infantile, childhood, adult, and odonto HPP. Among these, infantile HPP is characterized by early onset and high frequency of lethal outcome. Few studies have reported the phenotype and genetic characteristics of HPP in Chinese children. CASE PRESENTATION Three forms of HPP were identified in four unrelated patients from four different Chinese families, including one lethal infantile (patient 1), two childhood (patient 2 and 3) and one odonto HPP (patient 4). Six variants in the ALPL gene were identified, including five missense mutations and one frameshift mutation. Of which, none were reported previously in the Chinese population, and two were novel (c.359G > C: p.G120A and c.1017dupG: p.H340AfsX3). Patient 1 carrying a novel homozygous (c.359G > C) mutation showed respiratory distress and pneumonia at first day of his life. He presented nearly negligible level of serum ALP activity, overall skeletal hypominaralization and died at 3 months old. Patient 2, 3 and 4 were compound heterozygotes with decreased serum ALP activity. Patient 2 and 3 presented premature loss of deciduous teeth, muscle weakness and bone pain, whereas patient 4 had early loss of deciduous teeth only. All four pedigrees exhibited autosomal recessive pattern of inheritance. CONCLUSIONS In this study, six mutations in the ALPL gene were found in four Chinese HPP patients, two of which were novel: c.359G > C in exon 5 and c.1017dupG in exon 10. Our results strongly indicated that the novel mutation c.359G > C might be disease-causing and associated with severe infantile form of HPP.
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Affiliation(s)
- Xiaojian Mao
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 9 Jinsui Rd, Guangzhou, 510623, China
| | - Sichi Liu
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 9 Jinsui Rd, Guangzhou, 510623, China
| | - Yunting Lin
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 9 Jinsui Rd, Guangzhou, 510623, China
| | - Zhen Chen
- Department of Radiology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 9 Jinsui Rd., Guangzhou, 510623, China
| | - Yongxian Shao
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 9 Jinsui Rd, Guangzhou, 510623, China
| | - Qiaoli Yu
- Department of Dentistry, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 9 Jinsui Rd., Guangzhou, 510623, China
| | - Haiying Liu
- Clinical Laboratory, Guangzhou Women and Children's Medical Center, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 9 Jinsui Rd., Guangzhou, 510623, China
| | - Zhikun Lu
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 9 Jinsui Rd, Guangzhou, 510623, China
| | - Huiyin Sheng
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 9 Jinsui Rd, Guangzhou, 510623, China
| | - Xinshuo Lu
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 9 Jinsui Rd, Guangzhou, 510623, China
| | - Yonglan Huang
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 9 Jinsui Rd, Guangzhou, 510623, China
| | - Li Liu
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 9 Jinsui Rd, Guangzhou, 510623, China.
| | - Chunhua Zeng
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 9 Jinsui Rd, Guangzhou, 510623, China.
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Uday S, Matsumura T, Saraff V, Saito S, Orimo H, Högler W. Tissue non-specific alkaline phosphatase activity and mineralization capacity of bi-allelic mutations from severe perinatal and asymptomatic hypophosphatasia phenotypes: Results from an in vitro mutagenesis model. Bone 2019; 127:9-16. [PMID: 31146036 DOI: 10.1016/j.bone.2019.05.031] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/12/2019] [Revised: 05/24/2019] [Accepted: 05/25/2019] [Indexed: 10/26/2022]
Abstract
BACKGROUND Hypophosphatasia (HPP) is an inherited metabolic bone disease characterized by reduced mineralization due to mutations in the tissue non-specific alkaline phosphatase (ALPL) gene. HPP is clinically variable with extensive allelic heterogeneity in the ALPL gene. We report the findings of in vitro functional studies following site-directed mutagenesis in bi-allelic mutations causing extreme clinical phenotypes; severe perinatal and asymptomatic HPP. AIMS Elucidate genotype-phenotype correlation using in vitro functional studies and 3 dimensional (3D) ALP modelling. METHODS Clinical, biochemical and radiological features were recorded in two children with extreme HPP phenotypes: Subject 1 (S1): Perinatal HPP with compound heterozygous mutations (c.110T>C; c.532T>C); Subject 2 (S2): asymptomatic with homozygous missense mutation (c.715G>T). Plasmids created for mutants 1 c.110T>C (L37P), 2 c.532T>C (Y178H) and 3 c.715G>T (D239Y) using in vitro mutagenesis were transfected into human osteosarcoma (U2OS) cells and compared to wildtype (WT) and mock cDNA. ALP activity was measured using enzyme kinetics with p-nitrophenylphosphate. Mineral deposition was evaluated photometrically with Alizarin Red S staining after culture with mineralization medium. Western blot analysis was performed to identify the mature type protein expression (80 kDa). Mutations were located on a 3D ALP model. Co-transfection was performed to identify dominant negative effect of the mutants. RESULTS Phenotype: S1, had typical perinatal HPP phenotype at birth; extremely under-mineralized bones and pulmonary hypoplasia. S2, diagnosed incidentally by laboratory tests at 4 years, had normal growth, development, dentition and radiology. All S2's siblings (3 homozygous, 1 heterozygous) were asymptomatic. All subjects had typical biochemical features of HPP (low ALP, high serum pyridoxal-5'-phosphate), except the heterozygous sibling (normal ALP). Functional assay: Mutants 1 and 2 demonstrated negligible ALP activity and mineralization was 7.9% and 9.3% of WT, respectively. Mutant 3 demonstrated about 50% ALP activity and 15.5% mineralization of WT. On Western blot analysis, mutants 1 and 2 were detected as faint bands indicating reduced expression and mutant 3 was expressed as mature form protein with 50% of WT expression. Mutant 1 was located near the Glycosylphosphatidylinositol anchor, 2 at the core structure of the ALP protein and 3 at the periphery of the protein structure. Co-transfection did not reveal a dominant negative effect in any of the mutants. CONCLUSION Our findings expand the current knowledge of functional effect of individual mutations and the importance of their location in the ALP structure.
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Affiliation(s)
- Suma Uday
- Department of Endocrinology and Diabetes, Birmingham Women's and Children's Hospital, Birmingham, UK; Institute of Metabolism and Systems Research, University of Birmingham, Birmingham, UK
| | - Tomohiro Matsumura
- Department of Biochemistry and Molecular Biology, Graduate School of Medicine, Nippon Medical School, Tokyo, Japan
| | - Vrinda Saraff
- Department of Endocrinology and Diabetes, Birmingham Women's and Children's Hospital, Birmingham, UK
| | - Shiho Saito
- Department of Biochemistry and Molecular Biology, Graduate School of Medicine, Nippon Medical School, Tokyo, Japan
| | - Hideo Orimo
- Department of Biochemistry and Molecular Biology, Graduate School of Medicine, Nippon Medical School, Tokyo, Japan
| | - Wolfgang Högler
- Institute of Metabolism and Systems Research, University of Birmingham, Birmingham, UK; Department of Paediatrics and Adolescent Medicine, Johannes Kepler University, Linz, Austria.
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Choida V, Bubbear JS. Update on the management of hypophosphatasia. Ther Adv Musculoskelet Dis 2019; 11:1759720X19863997. [PMID: 31413732 PMCID: PMC6676257 DOI: 10.1177/1759720x19863997] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Accepted: 06/22/2019] [Indexed: 12/13/2022] Open
Abstract
Hypophosphatasia is a rare inherited disease caused by a loss of function mutations in the gene that codes for the tissue-nonspecific alkaline phosphatase enzyme. It is autosomally inherited and at least 388 different genetic defects have been identified. The clinical presentation is variable from a severe perinatal form, that is fatal if untreated, to adult-onset disease. This review covers the pathophysiology, diagnosis and current management option including the recently licensed enzyme replacement therapy asfotase alfa.
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Affiliation(s)
- V Choida
- Metabolic Unit, Royal National Orthopaedic Hospital, Stanmore, UK
| | - J S Bubbear
- Metabolic Unit, Royal National Orthopaedic Hospital, Brockley Hill, Stanmore, HA7 4LP, UK
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Ectopic Ocular Surface Calcification in Patients With Hypophosphatasia Treated With Asfotase Alfa. Cornea 2019; 38:896-900. [DOI: 10.1097/ico.0000000000001947] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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A homozygous missense variant in the alkaline phosphatase gene ALPL is associated with a severe form of canine hypophosphatasia. Sci Rep 2019; 9:973. [PMID: 30700765 PMCID: PMC6353930 DOI: 10.1038/s41598-018-37801-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Accepted: 12/13/2018] [Indexed: 12/25/2022] Open
Abstract
Inherited skeletal disorders affect both humans and animals. In the current study, we have performed series of clinical, pathological and genetic examinations to characterize a previously unreported skeletal disease in the Karelian Bear Dog (KBD) breed. The disease was recognized in seven KBD puppies with a variable presentation of skeletal hypomineralization, growth retardation, seizures and movement difficulties. Exome sequencing of one affected dog revealed a homozygous missense variant (c.1301T > G; p.V434G) in the tissue non-specific alkaline phosphatase gene, ALPL. The identified recessive variant showed full segregation with the disease in a cohort of 509 KBDs with a carrier frequency of 0.17 and was absent from 303 dogs from control breeds. In humans, recessive and dominant ALPL mutations cause hypophosphatasia (HPP), a metabolic bone disease with highly heterogeneous clinical manifestations, ranging from lethal perinatal hypomineralization to a relatively mild dental disease. Our study reports the first naturally occurring HPP in animals, resembling the human infantile form. The canine HPP model may serve as a preclinical model while a genetic test will assist in breeding programs.
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Freitas TQ, Franco AS, Pereira RMR. Improvement of bone microarchitecture parameters after 12 months of treatment with asfotase alfa in adult patient with hypophosphatasia: Case report. Medicine (Baltimore) 2018; 97:e13210. [PMID: 30508901 PMCID: PMC6283215 DOI: 10.1097/md.0000000000013210] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
RATIONALE Hypophosphatasia is an inborn error of metabolism that can appear any time in life, mainly with bone manifestations due to low alkaline phosphatase activity. Asfotase alfa is a specific enzyme reposition treatment that has shown promising results in children; however, there are few reports about the outcomes in adult patients. PATIENT CONCERNS A 36-year-old male presented with an early history of craniosynostosis, short stature, and multiple fractures since the age of 13 years-which needed numerous surgical corrections. He was admitted with a previous diagnosis of osteogenesis imperfecta, taking alendronate, calcium carbonate, cholecalciferol, and calcitriol. Bone mineral density was low (lumbar spine Z-score = -3.0 SD), with impairment of all parameters of high-resolution peripheral quantitative computed tomography (HR-pQCT). Kidney impairment was also observed with reduced creatinine clearance, nephrolithiasis, and nephrocalcinosis. DIAGNOSIS Alkaline phosphatase was unexpectedly low (6 U/L, reference value: 30-120 U/L), with high serum vitamin B6 (260 mcg/L, reference value: 5.2-34.1). Genetic testing showed a homozygous missense mutation in ALPL gene c.443 C>T: p.Thr148Ile. INTERVENTION Asfotase alfa was requested due to important bone deterioration, ambulatory disability, and kidney impairment. It was given subcutaneously 2 mg/kg per dose, 3 times a week, for 12 months before reassessment. OUTCOMES Bone mineral densities of the lumbar spine and whole body, besides almost all HR-pQCT microstructural parameters of the distal tibia, showed improvements and the patient was able to walk without assistant device. Kidney function did not further deteriorate. LESSONS Hypophosphatasia should be considered as a differential diagnosis in young patients with multiple fractures and kidney impairment, since the use of antiresorptive drugs, calcium and vitamin D, commonly used to treat fractures, worsen its symptoms and prognosis. A 12-month asfotase alfa treatment improved bone density and structural parameters even in an adult patient with late diagnosis.
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Rush ET. Childhood hypophosphatasia: to treat or not to treat. Orphanet J Rare Dis 2018; 13:116. [PMID: 30012160 PMCID: PMC6048713 DOI: 10.1186/s13023-018-0866-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Accepted: 07/03/2018] [Indexed: 11/25/2022] Open
Abstract
Background Hypophosphatasia (HPP) is a rare inborn error of metabolism that results from dysfunction of the tissue non-specific alkaline phosphatase enzyme. Its manifestations are extremely variable, ranging from early lethality to disease limited to the dentition. The disease is life-threatening when manifesting within the first six months of life, excepting the extremely rare benign perinatal hypophosphatasia. Childhood hypophosphatasia, defined as onset of symptoms between six months and eighteen years, can manifest as rickets, pain, decreased mobility, deficits of growth, and fractures. Historical treatment has generally involved a combination of dietary and rehabilitative interventions. Main document Asfotase alfa (Strensiq™), is a first-in-class bone-targeted recombinant tissue nonspecific alkaline phosphatase which has shown significant improvements in morbidity and mortality in patients with perinatal and infantile hypophosphatasia. Subsequent research has also shown improvements in morbidity for patients with childhood hypophosphatasia as measured by improvement in rickets, growth, strength, mobility, and quality of life. This enzyme replacement therapy has generally been well-tolerated, with most adverse reactions being mild-to-moderate in nature. The author shares their approach to decisions on commencement of ERT based from experience of managing approximately fifteen patients across the age spectrum. This approach focuses on assessing the severity of five key manifestations of childhood HPP: decreased mobility, pain, rickets, deficits of growth, and fractures.
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Affiliation(s)
- Eric T Rush
- Division of Clinical Genetics, Department of Pediatrics, Children's Mercy Kansas City, 2401 Gillham Road, Kansas City, MO, 64108, USA. .,Division of Endocrinology, Metabolism, and Genetics, Department of Internal Medicine, University of Kansas Medical Center, Kansas City, KS, 66160, USA.
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Dahir KM, Tilden DR, Warner JL, Bastarache L, Smith DK, Gifford A, Ramirez AH, Simmons JS, Black MM, Newman JH, Denny JC. Rare Variants in the Gene ALPL That Cause Hypophosphatasia Are Strongly Associated With Ovarian and Uterine Disorders. J Clin Endocrinol Metab 2018; 103:2234-2243. [PMID: 29659871 PMCID: PMC6456921 DOI: 10.1210/jc.2017-02676] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Accepted: 04/02/2018] [Indexed: 11/19/2022]
Abstract
CONTEXT Mutations in alkaline phosphatase (AlkP), liver/bone/kidney (ALPL), which encodes tissue-nonspecific isozyme AlkP, cause hypophosphatasia (HPP). HPP is suspected by a low-serum AlkP. We hypothesized that some patients with bone or dental disease have undiagnosed HPP, caused by ALPL variants. OBJECTIVE Our objective was to discover the prevalence of these gene variants in the Vanderbilt University DNA Biobank (BioVU) and to assess phenotypic associations. DESIGN We identified subjects in BioVU, a repository of DNA, that had at least one of three known, rare HPP disease-causing variants in ALPL: rs199669988, rs121918007, and/or rs121918002. To evaluate for phenotypic associations, we conducted a sequential phenome-wide association study of ALPL variants and then performed a de-identified manual record review to refine the phenotype. RESULTS Out of 25,822 genotyped individuals, we identified 52 women and 53 men with HPP disease-causing variants in ALPL, 7/1000. None had a clinical diagnosis of HPP. For patients with ALPL variants, the average serum AlkP levels were in the lower range of normal or lower. Forty percent of men and 62% of women had documented bone and/or dental disease, compatible with the diagnosis of HPP. Forty percent of the female patients had ovarian pathology or other gynecological abnormalities compared with 15% seen in controls. CONCLUSIONS Variants in the ALPL gene cause bone and dental disease in patients with and without the standard biomarker, low plasma AlkP. ALPL gene variants are more prevalent than currently reported and underdiagnosed. Gynecologic disease appears to be associated with HPP-causing variants in ALPL.
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Affiliation(s)
- Kathryn M Dahir
- Division of Endocrinology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
- Correspondence and Reprint Requests: Kathryn M. Dahir, MD, 21st Avenue South, Medical Center East 8210, Nashville, Tennessee 37232-8148. E-mail:
| | - Daniel R Tilden
- Department of Internal Medicine and Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Jeremy L Warner
- Division of Hematology and Oncology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
- Department of Biomedical Informatics, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Lisa Bastarache
- Department of Biomedical Informatics, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Derek K Smith
- Departments of Biostatistics and Oral Maxillofacial Surgery, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Aliya Gifford
- Department of Biomedical Informatics, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Andrea H Ramirez
- Division of Endocrinology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Jill S Simmons
- Division of Pediatric Endocrinology, Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Margo M Black
- Division of Pediatric Endocrinology, Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee
| | - John H Newman
- Division of Allergy, Pulmonary and Critical Care Medicine, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Josh C Denny
- Department of Biomedical Informatics, Vanderbilt University Medical Center, Nashville, Tennessee
- Division of General Internal Medicine, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
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Abstract
We review here clinical, pathophysiological, diagnostic, genetic and molecular aspects of Hypophosphatasia (HPP), a rare inherited metabolic disorder. The clinical presentation is a continuum ranging from a prenatal lethal form with no skeletal mineralization to a mild form with late adult onset presenting with nonpathognomonic symptoms. The prevalence of severe forms is low, whereas less severe forms are more frequently observed. The disease is caused by loss-of-function mutations in the ALPL gene encoding the Tissue Nonspecific Alkaline Phosphatase (TNSALP), a central regulator of mineralization. Severe forms are recessively inherited, whereas moderate forms are either recessively or dominantly inherited, and the more severe the disease is, the more often it is subject to recessive inheritance. The diagnosis is based on a constantly low alkaline phosphatase (AP) activity in serum and genetic testing that identifies ALPL mutations. More than 340 mutations have been identified and are responsible for the extraordinary clinical heterogeneity. A clear but imperfect genotype-phenotype correlation has been observed, suggesting that other genetic or environmental factors modulate the phenotype. Enzyme replacement therapy is now available for HPP, and other approaches, such as gene therapy, are currently being investigated.
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Affiliation(s)
- Etienne Mornet
- Unité de Génétique Constitutionnelle, Service de Biologie, Centre Hospitalier de Versailles, 177 rue de Versailles, 78150 Le Chesnay, France.
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Schmidt T, Mussawy H, Rolvien T, Hawellek T, Hubert J, Rüther W, Amling M, Barvencik F. Clinical, radiographic and biochemical characteristics of adult hypophosphatasia. Osteoporos Int 2017; 28:2653-2662. [PMID: 28547134 DOI: 10.1007/s00198-017-4087-z] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/27/2016] [Accepted: 05/10/2017] [Indexed: 01/28/2023]
Abstract
UNLABELLED In this study, we report on clinical, radiographic and biochemical characteristics of 38 patients with adult hypophosphatasia. High-resolution peripheral quantitative computed tomography showed alterations of bone microstructure in a subgroup of 14 patients. Pyridoxal-5-phosphate levels correlated with the occurrence of fractures and the number of symptoms. INTRODUCTION Hypophosphatasia (HPP) is a rare disorder with a wide range of clinical manifestations. A reduced enzymatic activity of alkaline phosphatase (ALP) is the key marker of the disease, causing an accumulation of ALP substrates such as pyridoxal-5-phosphate (PLP). The purpose of this retrospective study was to further characterize adult onset HPP. METHODS We assessed clinical, radiographic and laboratory characteristics of 38 adult patients with HPP. Diagnosis of HPP was established by the combination of low-serum ALP, raised PLP levels and typical symptoms and was genetically confirmed in 32 patients. Dual-energy X-ray absorptiometry (DXA) and laboratory data were available in most patients. High-resolution peripheral quantitative computed tomography (HR-pQCT) was performed in 14 patients. RESULTS Clinical characteristics included a wide spectrum of symptoms. A history of fracture was present in 15 patients (39%). Twenty-one patients (55%) complained about recurring headaches, 23 patients (61%) had recurring muscle pain, 4 patients (11%) suffered from severe muscle weakness and 18 patients (47%) showed dental abnormalities. Z-scores assessed by DXA were only slightly reduced in most adult HPP patients. HR-pQCT of 14 patients showed microstructural changes of trabecular and cortical bone compared to reference values of healthy subjects. The occurrence of fractures and multiple symptoms (>2 typical HPP symptoms) were associated with significantly elevated levels of PLP. CONCLUSION Adult HPP presents with a wide range of clinical symptoms and is not associated with low bone mass in general. PLP seems to be a good marker for disease severity in adult patients as its level is correlated with the occurrence of fractures and number of symptoms.
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Affiliation(s)
- T Schmidt
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestraße 59, 22529, Hamburg, Germany.
- Department of Orthopaedic Surgery, University Medical Center Hamburg-Eppendorf, Martinistraße 52, 20246, Hamburg, Germany.
| | - H Mussawy
- Department of Orthopaedic Surgery, University Medical Center Hamburg-Eppendorf, Martinistraße 52, 20246, Hamburg, Germany
| | - T Rolvien
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestraße 59, 22529, Hamburg, Germany
| | - T Hawellek
- Department of Orthopaedic Surgery, University Medical Center Hamburg-Eppendorf, Martinistraße 52, 20246, Hamburg, Germany
| | - J Hubert
- Department of Orthopaedic Surgery, University Medical Center Hamburg-Eppendorf, Martinistraße 52, 20246, Hamburg, Germany
| | - W Rüther
- Department of Orthopaedic Surgery, University Medical Center Hamburg-Eppendorf, Martinistraße 52, 20246, Hamburg, Germany
| | - M Amling
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestraße 59, 22529, Hamburg, Germany
| | - F Barvencik
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestraße 59, 22529, Hamburg, Germany
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Kishnani PS, Rush ET, Arundel P, Bishop N, Dahir K, Fraser W, Harmatz P, Linglart A, Munns CF, Nunes ME, Saal HM, Seefried L, Ozono K. Monitoring guidance for patients with hypophosphatasia treated with asfotase alfa. Mol Genet Metab 2017; 122:4-17. [PMID: 28888853 DOI: 10.1016/j.ymgme.2017.07.010] [Citation(s) in RCA: 70] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Revised: 07/20/2017] [Accepted: 07/24/2017] [Indexed: 11/15/2022]
Abstract
Hypophosphatasia (HPP) is a rare, inherited, systemic, metabolic disorder caused by autosomal recessive mutations or a single dominant-negative mutation in the gene encoding tissue-nonspecific alkaline phosphatase (TNSALP). The disease is associated with a broad range of signs, symptoms, and complications, including impaired skeletal mineralization, altered calcium and phosphate metabolism, recurrent fractures, pain, respiratory problems, impaired growth and mobility, premature tooth loss, developmental delay, and seizures. Asfotase alfa is a human, recombinant enzyme replacement therapy that is approved in many countries for the treatment of patients with HPP. To address the unmet need for guidance in the monitoring of patients receiving asfotase alfa, an international panel of physicians with experience in diagnosing and managing HPP convened in May 2016 to discuss treatment monitoring parameters. The panel discussions focused on recommendations for assessing and monitoring patients after the decision to treat with asfotase alfa had been made and did not include recommendations for whom to treat. Based on the consensus of panel members, this review provides guidance on the monitoring of patients with HPP during treatment with asfotase alfa, including recommendations for laboratory, efficacy, and safety assessments and the frequency with which these should be performed during the course of treatment. Recommended assessments are based on patient age and include regular monitoring of biochemistry, skeletal radiographs, respiratory function, growth, pain, mobility and motor function, and quality of life. Because of the systemic presentation of HPP, a coordinated, multidisciplinary, team-based, patient-focused approach is recommended in the management of patients receiving asfotase alfa. Monitoring of efficacy and safety outcomes must be tailored to the individual patient, depending on medical history, clinical manifestations, availability of resources in the clinical setting, and the clinician's professional judgment.
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Affiliation(s)
- Priya S Kishnani
- Division of Medical Genetics, Duke University Medical Center, Durham, NC 27710, USA.
| | - Eric T Rush
- Department of Pediatrics, University of Nebraska Medical Center, Omaha, NE 68198, USA(2)
| | - Paul Arundel
- Metabolic Bone Team, Sheffield Children's NHS Foundation Trust, Sheffield S10 2TH, UK
| | - Nick Bishop
- Academic Unit of Child Health, University of Sheffield and Sheffield Children's Hospital, Sheffield S10 2TH, UK
| | - Kathryn Dahir
- Division of Diabetes and Endocrinology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - William Fraser
- Norwich Medical School, Faculty of Medicine and Health Sciences, University of East Anglia, Norwich NR4 7UY, UK
| | - Paul Harmatz
- Pediatric Gastroenterology and Nutrition, UCSF Benioff Children's Hospital Oakland, Oakland, CA 94609, USA
| | - Agnès Linglart
- Service d'Endocrinologie Pédiatrique, Hôpital Bicêtre Paris-Sud, APHP, 94270 Le Kremlin Bicêtre, France
| | - Craig F Munns
- Paediatrics & Child Health, The Children's Hospital at Westmead, Westmead, NSW 2145, Australia; Sydney Medical School, University of Sydney, Sydney, NSW 2006, Australia
| | - Mark E Nunes
- Department of Pediatrics, University of California, San Diego, San Diego, CA 92093, USA
| | - Howard M Saal
- Division of Human Genetics, Cincinnati Children's Hospital, Cincinnati, OH 45229, USA
| | - Lothar Seefried
- Orthopedic Department, University of Würzburg, Würzburg, Bavaria 97074, Germany
| | - Keiichi Ozono
- Department of Pediatrics, Osaka University, Suita, Osaka 565-0871, Japan
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32
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Meah F, Basit A, Emanuele N, Emanuele MA. Hypophosphatasia: Review of Bone Mineral Metabolism, Pathophysiology, Clinical Presentation, Diagnosis, and Treatment. Clin Rev Bone Miner Metab 2017. [DOI: 10.1007/s12018-016-9225-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Tenorio J, Álvarez I, Riancho-Zarrabeitia L, Martos-Moreno GÁ, Mandrile G, de la Flor Crespo M, Sukchev M, Sherif M, Kramer I, Darnaude-Ortiz MT, Arias P, Gordo G, Dapía I, Martinez-Villanueva J, Gómez R, Iturzaeta JM, Otaify G, García-Unzueta M, Rubinacci A, Riancho JA, Aglan M, Temtamy S, Hamid MA, Argente J, Ruiz-Pérez VL, Heath KE, Lapunzina P. Molecular and clinical analysis ofALPLin a cohort of patients with suspicion of Hypophosphatasia. Am J Med Genet A 2017; 173:601-610. [DOI: 10.1002/ajmg.a.37991] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Accepted: 09/18/2016] [Indexed: 11/11/2022]
Affiliation(s)
- Jair Tenorio
- Institute of Medical and Molecular Genetics (INGEMM); Hospital Universitario La Paz, IdiPAZ; Universidad Autónoma de Madrid; Madrid Spain
- CIBERER; Centro de Investigación Biomédica en Red de Enfermedades Raras, ISCIII; Madrid Spain
| | | | | | - Gabriel Á. Martos-Moreno
- Department of Endocrinology; Hospital Universitario Niño Jesús, IIS La Princesa; Madrid Spain
- Department of Pediatrics; Universidad Autónoma de Madrid; Madrid Spain
- CIBEROBN, Centro de Investigación Biomédica en Red sobre Fisiopatología de la obesidad y nutrición; Instituto de Salud Carlos III; Madrid Spain
| | - Giorgia Mandrile
- Department of Medical Genetics; San Luigi University Hospital; Orbassano Italy
- Department Clinical and Biological Sciences; University of Torino; Torino Italy
| | | | - Mikhail Sukchev
- Diagnostic Specialist; Alexion Pharmaceuticals; Moscow Russia
| | - Mostafa Sherif
- Medical Division; Alexion Pharma Middle East; Dubai Media City United Arab Emirates
| | - Iza Kramer
- Department of Pediatrics; Privat Hospitalet Denmark; Charlottenlund Denmark
| | | | - Pedro Arias
- Institute of Medical and Molecular Genetics (INGEMM); Hospital Universitario La Paz, IdiPAZ; Universidad Autónoma de Madrid; Madrid Spain
- CIBERER; Centro de Investigación Biomédica en Red de Enfermedades Raras, ISCIII; Madrid Spain
| | - Gema Gordo
- Institute of Medical and Molecular Genetics (INGEMM); Hospital Universitario La Paz, IdiPAZ; Universidad Autónoma de Madrid; Madrid Spain
- CIBERER; Centro de Investigación Biomédica en Red de Enfermedades Raras, ISCIII; Madrid Spain
| | - Irene Dapía
- Institute of Medical and Molecular Genetics (INGEMM); Hospital Universitario La Paz, IdiPAZ; Universidad Autónoma de Madrid; Madrid Spain
- CIBERER; Centro de Investigación Biomédica en Red de Enfermedades Raras, ISCIII; Madrid Spain
| | | | - Rubén Gómez
- Department of Biochemistry; Hospital Universitario La Paz, IdiPaz; Madrid Spain
| | | | - Ghada Otaify
- Division of Human Genetics and Genome Research; Department of Clinical Genetics; National Research Centre, Cairo; Egypt
- Centre of Excellence for Human Genetics; National Research Centre; Cairo Egypt
| | - Mayte García-Unzueta
- Department of Clinical Biochemistry; Hospital Universitario Marqués Valdecilla, IDIVAL; Santander Spain
| | | | - José A. Riancho
- Department of Internal Medicine; Hospital Universitario Marqués Valdecilla, IDIVAL; University of Cantabria, RETICEF; Santander Spain
| | - Mona Aglan
- Division of Human Genetics and Genome Research; Department of Clinical Genetics; National Research Centre, Cairo; Egypt
- Centre of Excellence for Human Genetics; National Research Centre; Cairo Egypt
| | - Samia Temtamy
- Division of Human Genetics and Genome Research; Department of Clinical Genetics; National Research Centre, Cairo; Egypt
- Centre of Excellence for Human Genetics; National Research Centre; Cairo Egypt
| | - Mohamed Abdel Hamid
- Centre of Excellence for Human Genetics; National Research Centre; Cairo Egypt
- Division of Human Genetics and Genome Research; Department of Medical Molecular Genetics; National Research Centre; El Cairo Egypt
| | - Jesús Argente
- Department of Endocrinology; Hospital Universitario Niño Jesús, IIS La Princesa; Madrid Spain
- Department of Pediatrics; Universidad Autónoma de Madrid; Madrid Spain
- CIBEROBN, Centro de Investigación Biomédica en Red sobre Fisiopatología de la obesidad y nutrición; Instituto de Salud Carlos III; Madrid Spain
| | - Víctor L. Ruiz-Pérez
- CIBERER; Centro de Investigación Biomédica en Red de Enfermedades Raras, ISCIII; Madrid Spain
- Skeletal Dysplasia Multidisciplinary Unit (UMDE); Hospital Universitario La Paz; Madrid Spain
- Instituto de Investigaciones Biológicas (IB); Consejo Superior de Investigaciones Científicas (CSIC)-Universidad Autónoma de Madrid; Madrid Spain
| | - Karen E. Heath
- Institute of Medical and Molecular Genetics (INGEMM); Hospital Universitario La Paz, IdiPAZ; Universidad Autónoma de Madrid; Madrid Spain
- CIBERER; Centro de Investigación Biomédica en Red de Enfermedades Raras, ISCIII; Madrid Spain
- Skeletal Dysplasia Multidisciplinary Unit (UMDE); Hospital Universitario La Paz; Madrid Spain
| | - Pablo Lapunzina
- Institute of Medical and Molecular Genetics (INGEMM); Hospital Universitario La Paz, IdiPAZ; Universidad Autónoma de Madrid; Madrid Spain
- CIBERER; Centro de Investigación Biomédica en Red de Enfermedades Raras, ISCIII; Madrid Spain
- Skeletal Dysplasia Multidisciplinary Unit (UMDE); Hospital Universitario La Paz; Madrid Spain
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Abstract
Hypophosphatasia is a rare disorder due to a mutation in the ALPL gene encoding the alkaline phosphatase (ALP) leading to a diminished activity of the enzyme in bone, liver, and kidney. Hypophosphatasia is a heterogeneous disease, ranging from extreme life-threatening forms revealed at birth in young infants presenting with severely impaired bone mineralization, seizures, and hypercalcemia, to young adults with premature exfoliation of their teeth without any other symptom. We will review the challenges of the clinical, biochemical, radiological, and genetic diagnosis. Schematically, the diagnosis relies on low ALP levels and, in most cases, on the genetic defect in the ALPL gene. An enzyme replacement therapy is now developed for hypophosphatasia; early results in the severe form of the disease are extremely encouraging. However, multidisciplinary care remains the core of treatment of hypophosphatasia encompassing nutritional support, adjustment of calcium and phosphate intake, monitoring of vitamin D levels, careful and personalized physical therapy, and regular dental monitoring and care.
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Affiliation(s)
- Agnès Linglart
- Department of Pediatric Endocrinology and Diabetology for Children, APHP, Bicêtre Paris Sud, Le Kremlin Bicêtre, 94270, France.
- APHP, Reference Center for Rare Disorders of the Calcium and Phosphate Metabolism and Plateforme d'Expertise Paris Sud Maladies Rares, Le Kremlin Bicêtre, 94270, France.
| | - Martin Biosse-Duplan
- APHP, Reference Center for Rare Disorders of the Calcium and Phosphate Metabolism and Plateforme d'Expertise Paris Sud Maladies Rares, Le Kremlin Bicêtre, 94270, France
- Department of Odontology, APHP, Bretonneau Paris Nord Val de Seine, Paris, 75018, France
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