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Hassan N, Gregson CL, Tang H, van der Kamp M, Leo P, McInerney‐Leo AM, Zheng J, Brandi ML, Tang JCY, Fraser W, Stone MD, Grundberg E, Brown MA, Duncan EL, Tobias JH. Rare and Common Variants in GALNT3 May Affect Bone Mass Independently of Phosphate Metabolism. J Bone Miner Res 2023; 38:678-691. [PMID: 36824040 PMCID: PMC10729283 DOI: 10.1002/jbmr.4795] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Revised: 02/15/2023] [Accepted: 02/22/2023] [Indexed: 02/25/2023]
Abstract
Anabolic treatment options for osteoporosis remain limited. One approach to discovering novel anabolic drug targets is to identify genetic causes of extreme high bone mass (HBM). We investigated a pedigree with unexplained HBM within the UK HBM study, a national cohort of probands with HBM and their relatives. Whole exome sequencing (WES) in a family with HBM identified a rare heterozygous missense variant (NM_004482.4:c.1657C > T, p.Arg553Trp) in GALNT3, segregating appropriately. Interrogation of data from the UK HBM study and the Anglo-Australasian Osteoporosis Genetics Consortium (AOGC) revealed an unrelated individual with HBM with another rare heterozygous variant (NM_004482.4:c.831 T > A, p.Asp277Glu) within the same gene. In silico protein modeling predicted that p.Arg553Trp would disrupt salt-bridge interactions, causing instability of GALNT3, and that p.Asp277Glu would disrupt manganese binding and consequently GALNT3 catalytic function. Bi-allelic loss-of-function GALNT3 mutations alter FGF23 metabolism, resulting in hyperphosphatemia and causing familial tumoral calcinosis (FTC). However, bone mineral density (BMD) in FTC cases, when reported, has been either normal or low. Common variants in the GALNT3 locus show genome-wide significant associations with lumbar, femoral neck, and total body BMD. However, no significant associations with BMD are observed at loci coding for FGF23, its receptor FGFR1, or coreceptor klotho. Mendelian randomization analysis, using expression quantitative trait loci (eQTL) data from primary human osteoblasts and genome-wide association studies data from UK Biobank, suggested increased expression of GALNT3 reduces total body, lumbar spine, and femoral neck BMD but has no effect on phosphate concentrations. In conclusion, rare heterozygous loss-of-function variants in GALNT3 may cause HBM without altering phosphate concentration. These findings suggest that GALNT3 may affect BMD through pathways other than FGF23 regulation, the identification of which may yield novel anabolic drug targets for osteoporosis. © 2023 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).
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Affiliation(s)
- Neelam Hassan
- Musculoskeletal Research Unit, Translational Health Sciences, Bristol Medical SchoolUniversity of BristolBristolUK
| | - Celia L. Gregson
- Musculoskeletal Research Unit, Translational Health Sciences, Bristol Medical SchoolUniversity of BristolBristolUK
- MRC Integrated Epidemiology Unit, Population Health Sciences, Bristol Medical SchoolUniversity of BristolBristolUK
| | - Haotian Tang
- MRC Integrated Epidemiology Unit, Population Health Sciences, Bristol Medical SchoolUniversity of BristolBristolUK
| | | | - Paul Leo
- Faculty of Health, Translational Genomics Group, Institute of Health and Biomedical InnovationQueensland University of TechnologyBrisbaneQueenslandAustralia
| | - Aideen M. McInerney‐Leo
- The Faculty of Medicine, Frazer InstituteThe University of QueenslandWoolloongabbaQueenslandAustralia
| | - Jie Zheng
- MRC Integrated Epidemiology Unit, Population Health Sciences, Bristol Medical SchoolUniversity of BristolBristolUK
- Department of Endocrine and Metabolic Diseases, Shanghai Institute of Endocrine and Metabolic Diseases, Ruijin HospitalShanghai Jiao Tong University School of MedicineShanghaiChina
- Shanghai National Clinical Research Center for metabolic Diseases, Key Laboratory for Endocrine and Metabolic Diseases of the National Health Commission of the PR ChinaShanghai Jiao Tong University School of MedicineShanghaiChina
- Shanghai Key Laboratory for Endocrine Tumor, State Key Laboratory of Medical Genomics, Ruijin HospitalShanghai Jiao Tong University School of MedicineShanghaiChina
| | | | - Jonathan C. Y. Tang
- Norwich Medical SchoolUniversity of East AngliaNorwichUK
- Clinical Biochemistry, Departments of Laboratory MedicineNorfolk and Norwich University Hospital NHS Foundation TrustNorwichUK
| | - William Fraser
- Norwich Medical SchoolUniversity of East AngliaNorwichUK
- Department of Diabetes, Endocrinology and Clinical BiochemistryNorfolk and Norwich University Hospital NHS Foundation TrustNorwichUK
| | - Michael D. Stone
- University Hospital LlandoughCardiff & Vale University Health BoardCardiffUK
| | - Elin Grundberg
- Genomic Medicine CenterChildren's Mercy Kansas CityKansas CityMissouriUSA
| | | | | | - Emma L. Duncan
- Department of Twin Research and Genetic Epidemiology, School of Life Course & Population Sciences, Faculty of Life Sciences and MedicineKing's College LondonLondonUK
| | - Jonathan H. Tobias
- Musculoskeletal Research Unit, Translational Health Sciences, Bristol Medical SchoolUniversity of BristolBristolUK
- MRC Integrated Epidemiology Unit, Population Health Sciences, Bristol Medical SchoolUniversity of BristolBristolUK
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Domazetovic V, Falsetti I, Ciuffi S, Iantomasi T, Marcucci G, Vincenzini MT, Brandi ML. Effect of Oxidative Stress-Induced Apoptosis on Active FGF23 Levels in MLO-Y4 Cells: The Protective Role of 17-β-Estradiol. Int J Mol Sci 2022; 23:ijms23042103. [PMID: 35216216 PMCID: PMC8879671 DOI: 10.3390/ijms23042103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 02/10/2022] [Accepted: 02/11/2022] [Indexed: 12/04/2022] Open
Abstract
The discovery that osteocytes secrete phosphaturic fibroblast growth factor 23 (FGF23) has defined bone as an endocrine organ. However, the autocrine and paracrine functions of FGF23 are still unknown. The present study focuses on the cellular and molecular mechanisms involved in the complex control of FGF23 production and local bone remodeling functions. FGF23 was assayed using ELISA kit in the presence or absence of 17β–estradiol in starved MLO-Y4 osteocytes. In these cells, a relationship between oxidative stress-induced apoptosis and up-regulation of active FGF23 levels due to MAP Kinases activation with involvement of the transcriptional factor (NF-kB) has been demonstrated. The active FGF23 increase can be due to up-regulation of its expression and post-transcriptional modifications. 17β–estradiol prevents the increase of FGF23 by inhibiting JNK and NF-kB activation, osteocyte apoptosis and by the down-regulation of osteoclastogenic factors, such as sclerostin. No alteration in the levels of dentin matrix protein 1, a FGF23 negative regulator, has been determined. The results of this study identify biological targets on which drugs and estrogen may act to control active FGF23 levels in oxidative stress-related bone and non-bone inflammatory diseases.
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Affiliation(s)
- Vladana Domazetovic
- Department of Experimental and Clinical Biomedical Sciences, University of Florence, 50134 Florence, Italy; (V.D.); (I.F.); (S.C.); (T.I.); (G.M.); (M.T.V.)
| | - Irene Falsetti
- Department of Experimental and Clinical Biomedical Sciences, University of Florence, 50134 Florence, Italy; (V.D.); (I.F.); (S.C.); (T.I.); (G.M.); (M.T.V.)
| | - Simone Ciuffi
- Department of Experimental and Clinical Biomedical Sciences, University of Florence, 50134 Florence, Italy; (V.D.); (I.F.); (S.C.); (T.I.); (G.M.); (M.T.V.)
| | - Teresa Iantomasi
- Department of Experimental and Clinical Biomedical Sciences, University of Florence, 50134 Florence, Italy; (V.D.); (I.F.); (S.C.); (T.I.); (G.M.); (M.T.V.)
| | - Gemma Marcucci
- Department of Experimental and Clinical Biomedical Sciences, University of Florence, 50134 Florence, Italy; (V.D.); (I.F.); (S.C.); (T.I.); (G.M.); (M.T.V.)
| | - Maria Teresa Vincenzini
- Department of Experimental and Clinical Biomedical Sciences, University of Florence, 50134 Florence, Italy; (V.D.); (I.F.); (S.C.); (T.I.); (G.M.); (M.T.V.)
| | - Maria Luisa Brandi
- Fondazione Italiana Ricerca sulle Malattie dell’Osso (FIRMO Onlus), 50141 Florence, Italy
- Correspondence:
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3
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Kato K, Hansen L, Clausen H. Polypeptide N-acetylgalactosaminyltransferase-Associated Phenotypes in Mammals. Molecules 2021; 26:5504. [PMID: 34576978 PMCID: PMC8472655 DOI: 10.3390/molecules26185504] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Revised: 09/07/2021] [Accepted: 09/08/2021] [Indexed: 01/31/2023] Open
Abstract
Mucin-type O-glycosylation involves the attachment of glycans to an initial O-linked N-acetylgalactosamine (GalNAc) on serine and threonine residues on proteins. This process in mammals is initiated and regulated by a large family of 20 UDP-GalNAc: polypeptide N-acetylgalactosaminyltransferases (GalNAc-Ts) (EC 2.4.1.41). The enzymes are encoded by a large gene family (GALNTs). Two of these genes, GALNT2 and GALNT3, are known as monogenic autosomal recessive inherited disease genes with well characterized phenotypes, whereas a broad spectrum of phenotypes is associated with the remaining 18 genes. Until recently, the overlapping functionality of the 20 members of the enzyme family has hindered characterizing the specific biological roles of individual enzymes. However, recent evidence suggests that these enzymes do not have full functional redundancy and may serve specific purposes that are found in the different phenotypes described. Here, we summarize the current knowledge of GALNT and associated phenotypes.
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Affiliation(s)
- Kentaro Kato
- Department of Eco-Epidemiology, Institute of Tropical Medicine, Nagasaki University, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan
- School of Tropical Medicine and Global Health, Nagasaki University, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan
| | - Lars Hansen
- Copenhagen Center for Glycomics, Department of Cellular and Molecular Medicine, Mærsk Building, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen N, Denmark;
| | - Henrik Clausen
- Copenhagen Center for Glycomics, Department of Cellular and Molecular Medicine, Mærsk Building, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen N, Denmark;
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4
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Guerra MG, Videira T, de Fonseca D, Vieira R, Dos Santos J, Pinto S. Hyperphosphataemic familial tumoral calcinosis: case report of a rare and challenging disease. Scand J Rheumatol 2020; 49:80-81. [PMID: 31213107 DOI: 10.1080/03009742.2019.1602883] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/31/2019] [Indexed: 01/01/2023]
Affiliation(s)
- M G Guerra
- Rheumatology Department, Vila Nova de Gaia/Espinho Hospital, Unit I, Vila Nova de Gaia, Portugal
| | - Tmfc Videira
- Rheumatology Department, Vila Nova de Gaia/Espinho Hospital, Unit I, Vila Nova de Gaia, Portugal
| | - Dmgg de Fonseca
- Rheumatology Department, Vila Nova de Gaia/Espinho Hospital, Unit I, Vila Nova de Gaia, Portugal
| | - Rcc Vieira
- Rheumatology Department, Vila Nova de Gaia/Espinho Hospital, Unit I, Vila Nova de Gaia, Portugal
| | - Jpaa Dos Santos
- Rheumatology Department, Vila Nova de Gaia/Espinho Hospital, Unit I, Vila Nova de Gaia, Portugal
| | - Spam Pinto
- Rheumatology Department, Vila Nova de Gaia/Espinho Hospital, Unit I, Vila Nova de Gaia, Portugal
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5
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Boyce AM, Lee AE, Roszko KL, Gafni RI. Hyperphosphatemic Tumoral Calcinosis: Pathogenesis, Clinical Presentation, and Challenges in Management. Front Endocrinol (Lausanne) 2020; 11:293. [PMID: 32457699 PMCID: PMC7225339 DOI: 10.3389/fendo.2020.00293] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Accepted: 04/20/2020] [Indexed: 02/02/2023] Open
Abstract
Hyperphosphatemic familial tumoral calcinosis (HFTC) is a rare and disabling disorder of fibroblast growth factor 23 (FGF23) deficiency or resistance. The disorder is manifest by hyperphosphatemia, inappropriately increased tubular reabsorption of phosphate and 1,25-dihydroxy-Vitamin D, and ectopic calcifications. HFTC has been associated with autosomal recessive pathogenic variants in: (1) the gene encoding FGF23; (2) GALNT3, which encodes a protein responsible for FGF23 glycosylation; and (3) KL, the gene encoding KLOTHO, a critical co-receptor for FGF23 signaling. An acquired autoimmune form of hyperphosphatemic tumoral calcinosis has also been reported. Periarticular tumoral calcinosis is the primary cause of disability in HFTC, leading to pain, reduced range-of-motion, and impaired physical function. Inflammatory disease is also prominent, including diaphysitis with cortical hyperostosis. Multiple treatment strategies have attempted to manage blood phosphate, reduce pain and inflammation, and address calcifications and their complications. Unfortunately, efficacy data are limited to case reports and small cohorts, and no clearly effective therapies have been identified. The purpose of this review is to provide a background on pathogenesis and clinical presentation in HFTC, discuss current approaches to clinical management, and outline critical areas of need for future research.
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6
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Dauchez A, Souffir C, Quartier P, Baujat G, Briot K, Roux C. Hyperphosphatemic Familial Tumoral Calcinosis With Galnt3 Mutation: Transient Response to Anti-Interleukin-1 Treatments. JBMR Plus 2019; 3:e10185. [PMID: 31372591 PMCID: PMC6659445 DOI: 10.1002/jbm4.10185] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Revised: 02/04/2019] [Accepted: 02/06/2019] [Indexed: 01/12/2023] Open
Abstract
Hyperphosphatemic familial tumoral calcinosis (HFTC) is a rare autosomal recessive disease caused by mutations in genes involved in phosphate homeostasis and characterized by high serum phosphate concentration and occurrence of ectopic calcifications. Management of the disease includes lowering of phosphate concentration and, when clinically necessary, debulking surgery of calcifications. In addition, high inflammatory disease flares can occur. Our case is about a patient with GALNT3 mutation and several localizations of refractory calcinosis. Assuming HFTC acts like an auto-inflammatory syndrome, we report the effect of anti-interleukine-1 therapies on the evolution of the disease. Anakinra (100 mg, then 200 mg subcutaneous daily) and canakinumab (300 mg every 4 weeks) were sequentially given to the patient. Anti-IL-1 therapy was effective in controlling inflammatory flares; however, it did not prevent extension of calcinosis. © 2019 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.
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Affiliation(s)
- Astrid Dauchez
- Rheumatology Department Cochin Hospital Assistance Publique - Hôpitaux de Paris Paris France
| | - Camille Souffir
- Rheumatology Department Cochin Hospital Assistance Publique - Hôpitaux de Paris Paris France.,Paris Descartes University Paris France
| | - Pierre Quartier
- Paris Descartes University Paris France.,Paediatric Immunology - Haematology and Rheumatology Department Necker Hospital Assistance Publique - Hôpitaux de Paris Paris France.,IMAGINE Institute Paris France.,French National Reference Centre for Inflammatory Rheumatism and Autoimmune Systemic Disease in Children (RAISE)
| | - Geneviève Baujat
- IMAGINE Institute Paris France.,National Reference Center for Genetic Bone Diseases
| | - Karine Briot
- Rheumatology Department Cochin Hospital Assistance Publique - Hôpitaux de Paris Paris France.,National Reference Center for Genetic Bone Diseases
| | - Christian Roux
- Rheumatology Department Cochin Hospital Assistance Publique - Hôpitaux de Paris Paris France.,Paris Descartes University Paris France.,National Reference Center for Genetic Bone Diseases
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7
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Kışla Ekinci RM, Gürbüz F, Balcı S, Bişgin A, Taştan M, Yüksel B, Yılmaz M. Hyperphosphatemic Familial Tumoral Calcinosis in Two Siblings with a Novel Mutation in GALNT3 Gene: Experience from Southern Turkey. J Clin Res Pediatr Endocrinol 2019; 11:94-99. [PMID: 30015621 PMCID: PMC6398194 DOI: 10.4274/jcrpe.galenos.2018.2018.0134] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Accepted: 07/17/2018] [Indexed: 12/01/2022] Open
Abstract
Inactivating autosomal recessive mutations in fibroblast growth factor 23 (FGF23), klotho (KL) and polypeptide N-acetylgalactosaminotransferase 3 (GALNT3) genes lead to a rare disorder, hyperphosphatemic familial tumoral calcinosis (HFTC). Patients with HFTC present with hyperphosphatemia and tumor like soft tissue calcifications. Although 78% of patients develop their first symptoms between the ages of 2-13 years, diagnosis is usually delayed until adulthood. Some individuals with the same genetic defect develop a condition named hyperphosphatemic hyperostosis syndrome. Herein we report two siblings suffering from periarticular, warm, hard and tender subcutaneous masses. Subcutaneous calcifications were present on X-ray and biopsy results were consistent with calcinosis in both patients. Laboratory results showed marked hyperphosphatemia and elevated renal tubular phosphate reabsorption rates, normal renal function tests and normal serum 25-hydroxyvitamin D levels. Thus, we suspected HFTC and performed next generation sequencing for the GALNT3 gene, reported as the most frequent cause. A novel homozygote P85Rfs*6 (c.254_255delCT) mutation in GALNT3 was identified in both siblings. Our report adds two new patients to the literature about this rare genetic disease and suggests that small deletions in the GALNT3 gene may be related with HFTC phenotype.
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Affiliation(s)
| | - Fatih Gürbüz
- Çukurova University Faculty of Medicine, Department of Pediatric Endocrinology, Adana, Turkey
| | - Sibel Balcı
- Çukurova University Faculty of Medicine, Department of Pediatric Rheumatology, Adana, Turkey
| | - Atıl Bişgin
- Çukurova University Faculty of Medicine, Department of Medical Genetics, Adana, Turkey
| | - Mehmet Taştan
- Çukurova University Faculty of Medicine, Department of Pediatric Endocrinology, Adana, Turkey
| | - Bilgin Yüksel
- Çukurova University Faculty of Medicine, Department of Pediatric Endocrinology, Adana, Turkey
| | - Mustafa Yılmaz
- Çukurova University Faculty of Medicine, Department of Pediatric Rheumatology, Adana, Turkey
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8
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Marcucci G, Masi L, Ferrarì S, Haffner D, Javaid MK, Kamenický P, Reginster JY, Rizzoli R, Brandi ML. Phosphate wasting disorders in adults. Osteoporos Int 2018; 29:2369-2387. [PMID: 30014155 DOI: 10.1007/s00198-018-4618-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Accepted: 06/19/2018] [Indexed: 12/14/2022]
Abstract
A cause of hypophosphatemia is phosphate wasting disorders. Knowledge concerning mechanisms involved in phosphate wasting disorders has greatly increased in the last decade by the identification of phosphatonins, among them FGF-23. FGF-23 is a primarily bone derived factor decreasing renal tubular reabsorption of phosphate and the synthesis of calcitriol. Currently, pharmacological treatment of these disorders offers limited efficacy and is potentially associated to gastrointestinal, renal, and parathyroid complications; therefore, efforts have been directed toward newer pharmacological strategies that target the FGF-23 pathway. This review focuses on phosphate metabolism, its main regulators, and phosphate wasting disorders in adults, highlighting the main issues related to diagnosis and current and new potential treatments.
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Affiliation(s)
- G Marcucci
- Metabolic Bone Diseases Unit, Department of Surgery and Translational Medicine, University of Florence, Florence, Italy
| | - L Masi
- Metabolic Bone Diseases Unit, Department of Surgery and Translational Medicine, University of Florence, Florence, Italy
| | - S Ferrarì
- Division of Bone Diseases, Geneva University Hospitals and Faculty of Medicine, Geneva, Switzerland
| | - D Haffner
- Department of Pediatric Kidney, Liver and Metabolic Diseases, Hannover Medical School, Hannover, Germany
| | - M K Javaid
- Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford, UK
| | - P Kamenický
- Service d'Endocrinologie et des Maladies de la Reproduction, Centre de référence des Maladies Rares du métabolisme du calcium et du phosphore, Hopital de Bicêtre - AP-HP, 94275, Le Kremlin-Bicêtre, France
| | - J-Y Reginster
- Department of Public Health, Epidemiology and Health Economics, University of Liège, Liège, Belgium
| | - R Rizzoli
- Division of Bone Diseases, Geneva University Hospitals and Faculty of Medicine, Geneva, Switzerland
| | - M L Brandi
- Metabolic Bone Diseases Unit, Department of Surgery and Translational Medicine, University of Florence, Florence, Italy.
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9
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Ramnitz MS, Gourh P, Goldbach-Mansky R, Wodajo F, Ichikawa S, Econs MJ, White KE, Molinolo A, Chen MY, Heller T, Del Rivero J, Seo-Mayer P, Arabshahi B, Jackson MB, Hatab S, McCarthy E, Guthrie LC, Brillante BA, Gafni RI, Collins MT. Phenotypic and Genotypic Characterization and Treatment of a Cohort With Familial Tumoral Calcinosis/Hyperostosis-Hyperphosphatemia Syndrome. J Bone Miner Res 2016; 31:1845-1854. [PMID: 27164190 PMCID: PMC5071128 DOI: 10.1002/jbmr.2870] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Revised: 04/22/2016] [Accepted: 05/09/2016] [Indexed: 01/05/2023]
Abstract
Familial tumoral calcinosis (FTC)/hyperostosis-hyperphosphatemia syndrome (HHS) is a rare disorder caused by mutations in the genes encoding fibroblast growth factor-23 (FGF23), N-acetylgalactosaminyltransferase 3 (GALNT3), or KLOTHO. The result is functional deficiency of, or resistance to, intact FGF23 (iFGF23), causing hyperphosphatemia, increased renal tubular reabsorption of phosphorus (TRP), elevated or inappropriately normal 1,25-dihydroxyvitamin D3 (1,25D), ectopic calcifications, and/or diaphyseal hyperostosis. Eight subjects with FTC/HHS were studied and treated. Clinical manifestations varied, even within families, ranging from asymptomatic to large, disabling calcifications. All subjects had hyperphosphatemia, increased TRP, and elevated or inappropriately normal 1,25D. C-terminal FGF23 was markedly elevated whereas iFGF23 was comparatively low, consistent with increased FGF23 cleavage. Radiographs ranged from diaphyseal hyperostosis to massive calcification. Two subjects with severe calcifications also had overwhelming systemic inflammation and elevated C-reactive protein (CRP). GALNT3 mutations were identified in seven subjects; no causative mutation was found in the eighth. Biopsies from four subjects showed ectopic calcification and chronic inflammation, with areas of heterotopic ossification observed in one subject. Treatment with low phosphate diet, phosphate binders, and phosphaturia-inducing therapies was prescribed with variable response. One subject experienced complete resolution of a calcific mass after 13 months of medical treatment. In the two subjects with systemic inflammation, interleukin-1 (IL-1) antagonists significantly decreased CRP levels with resolution of calcinosis cutis and perilesional inflammation in one subject and improvement of overall well-being in both subjects. This cohort expands the phenotype and genotype of FTC/HHS and demonstrates the range of clinical manifestations despite similar biochemical profiles and genetic mutations. Overwhelming systemic inflammation has not been described previously in FTC/HHS; the response to IL-1 antagonists suggests that anti-inflammatory drugs may be useful adjuvants. In addition, this is the first description of heterotopic ossification reported in FTC/HHS, possibly mediated by the adjacent inflammation. © 2016 American Society for Bone and Mineral Research.
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Affiliation(s)
- Mary Scott Ramnitz
- Skeletal Clinical Studies Unit, Craniofacial and Skeletal Diseases Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
| | - Pravitt Gourh
- National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Raphaela Goldbach-Mansky
- National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Felasfa Wodajo
- Musculoskeletal Tumor Surgery, Virginia Cancer Specialists, Fairfax, VA, USA
| | - Shoji Ichikawa
- Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Michael J Econs
- Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, USA
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Kenneth E White
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Alfredo Molinolo
- Skeletal Clinical Studies Unit, Craniofacial and Skeletal Diseases Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
| | - Marcus Y Chen
- National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Theo Heller
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Jaydira Del Rivero
- National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Patricia Seo-Mayer
- Division of Nephrology and Hypertension, Pediatric Specialists of Virginia and Georgetown University School of Medicine, Fairfax, VA, USA
| | - Bita Arabshahi
- Department of Rheumatology, Pediatric Specialists of Virginia, Fairfax, VA, USA
| | - Malaka B Jackson
- Department of Pediatric Endocrinology, University of South Carolina School of Medicine, Columbia, SC, USA
| | - Sarah Hatab
- Department of Pediatric Endocrinology, Emory University School of Medicine, Atlanta, GA, USA
| | - Edward McCarthy
- Department of Pathology, Johns Hopkins Hospital, Baltimore, MD, USA
| | - Lori C Guthrie
- Skeletal Clinical Studies Unit, Craniofacial and Skeletal Diseases Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
| | - Beth A Brillante
- Skeletal Clinical Studies Unit, Craniofacial and Skeletal Diseases Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
| | - Rachel I Gafni
- Skeletal Clinical Studies Unit, Craniofacial and Skeletal Diseases Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
| | - Michael T Collins
- Skeletal Clinical Studies Unit, Craniofacial and Skeletal Diseases Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA.
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