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Abstract
PURPOSE OF REVIEW X-Linked hypophosphatemia (XLH) is the most common genetic cause of rickets. This review describes advances in the management of XLH using burosumab which was FDA approved for treating children with XLH in 2018. RECENT FINDINGS Elevated FGF23 in XLH leads to systemic hypophosphatemia and several musculoskeletal manifestations, including rachitic bone deformities, impaired growth, dental abscesses, insufficiency fractures, osteoarthritis, and enthesopathy, with lifelong consequences for physical function and quality of life. Burosumab treatment has demonstrated clinical improvement of rickets and growth in children, including during a randomized controlled trial compared with conventional therapy. Burosumab also improved pseudofracture healing in adults. Burosumab led to greater improvement in rickets and growth than conventional therapy. However, many questions remain regarding the impact of burosumab on several outcomes, including final height, nephrocalcinosis, dental disease, enthesopathy, and surgical interventions.
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Affiliation(s)
- Erik A Imel
- Department of Medicine, Indiana University School of Medicine, 1120 West Michigan Street, CL 365, Indianapolis, IN, 46202-5111, USA.
- Department of Pediatrics, Indiana University School of Medicine, 1120 West Michigan Street, CL 365, Indianapolis, IN, 46202-5111, USA.
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152
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Vandewalle B, Amorim M, Ramos D, Azevedo S, Alves I, Francisco T, Pinto H, Sousa S. Value-based decision-making for orphan drugs with multiple criteria decision analysis: burosumab for the treatment of X-linked hypophosphatemia. Curr Med Res Opin 2021; 37:1021-1030. [PMID: 33733971 DOI: 10.1080/03007995.2021.1904861] [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] [Indexed: 10/21/2022]
Abstract
OBJECTIVE Burosumab is an orphan medicinal product (OMP) approved in Europe for the treatment of X-linked hypophosphatemia (XLH). The aim of this study was to assess the value of burosumab versus conventional therapy for the treatment of paediatric XLH, through a multi-criteria decision analysis (MCDA) framework for health technology assessment (HTA) of OMPs in Portugal. METHODS The MCDA framework considered 14 criteria related to disease burden, therapeutic value and economic burden. A multidisciplinary panel of national stakeholders participated in a two-phase exercise. In the first phase, relative weights and part-worth utilities for the criteria and their levels were elicited and a reimbursement likelihood function was calibrated through adaptive conjoint analysis. In the second phase, burosumab and conventional therapy were assessed against the criteria, providing a global value score (0-100) and reimbursement likelihood (0-100%) for both. RESULTS Of the 14 criteria, disease burden, therapeutic value and economic burden criteria represented 27.29%, 57.17% and 15.53% of the total weight in the decision, respectively. All disease burden and some therapeutic value criteria, typically not included in traditional HTA, represented 47.88% of the total weight. Burosumab was unanimously considered superior to conventional therapy, with an average (range) global value score of 84.96 (82.48-86.54) against 48.06 (43.37-57.68), and reimbursement likelihood of 97.50% (96.78%-98.32%) against 43.66% (31.48%-68.73%), respectively. CONCLUSIONS MCDA represents a powerful tool in HTA decision-making for OMPs. The results of this MCDA acknowledge burosumab as a disease-modifying drug, deemed superior to conventional therapy for the treatment of paediatric XLH.
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Affiliation(s)
| | | | | | | | - Inês Alves
- Associação Nacional de Displasias Ósseas, Évora, Portugal
| | - Telma Francisco
- Centro Hospitalar Universitário Lisboa Central, Lisbon, Portugal
| | - Helena Pinto
- Centro Hospitalar Universitário de São João, Porto, Portugal
| | - Sérgio Sousa
- Centro Hospitalar e Universitário de Coimbra, Coimbra, Portugal
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153
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Jeong IH, Yoo JH, Kim N. A pathogenic PHEX variant (c.1483-1G>C) in a Korean patient with X-linked hypophosphatemic rickets. Ann Pediatr Endocrinol Metab 2021; 26:130-133. [PMID: 34218635 PMCID: PMC8255857 DOI: 10.6065/apem.2040186.093] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Accepted: 09/21/2020] [Indexed: 11/28/2022] Open
Abstract
X-linked hypophosphatemic rickets is an X-linked dominantly inherited disorder characterized by defects in renal phosphate transport leading to phosphate wasting and hypophosphatemia. In this report, we describe a case of X-linked hypophosphatemic rickets in a patient with a rare pathogenic PHEX variant. The 25-year-old female patient came to our clinic for genetic counseling regarding presumed genetic disease and pregnancy. When she was 9 years old, she had been diagnosed with vitamin D-resistant rickets based on laboratory results and symptoms. She had undergone orthopedic surgery due to bowing leg deformities. Since then, she was intermittently self-prescribing oral phosphate and calcium supplements. At 25 years old, she was diagnosed with X-linked hypophosphatemic rickets with a rare pathogenic PHEX variant (c.1483-1G>C) by next-generation sequencing. This is the second report of the c.1483-1G>C variant to date, and her pathogenicity was confirmed based on the most recent guideline. Traditionally, the disease had been diagnosed mostly based on clinical findings. However, with advancements in genetic testing, genetic confirmation has become an imperative part of diagnostic workup. Herein, we report a 25-year-old female Korean patient diagnosed with X-linked hypophosphatemic rickets harboring a rare pathogenic PHEX variant.
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Affiliation(s)
- In Hwa Jeong
- Department of Laboratory Medicine, Dong-A University Hospital, Busan, Korea
| | - Jae-Ho Yoo
- Department of Pediatrics, Dong-A University Hospital, Busan, Korea
| | - Namhee Kim
- Department of Laboratory Medicine, Dong-A University Hospital, Busan, Korea,Address for correspondence: Namhee Kim Department of Laboratory Medicine, Dong-A University Hospital, 26 Daesingongwon-ro, Seo-gu, Busan 49201, Korea
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154
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Yuan Y, Jagga S, Martins JS, Rana R, Pajevic PD, Liu ES. Impaired 1,25 dihydroxyvitamin D3 action and hypophosphatemia underlie the altered lacuno-canalicular remodeling observed in the Hyp mouse model of XLH. PLoS One 2021; 16:e0252348. [PMID: 34043707 PMCID: PMC8158930 DOI: 10.1371/journal.pone.0252348] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Accepted: 05/12/2021] [Indexed: 11/28/2022] Open
Abstract
Osteocytes remodel the perilacunar matrix and canaliculi. X-linked hypophosphatemia (XLH) is characterized by elevated serum levels of fibroblast growth factor 23 (FGF23), leading to decreased 1,25 dihydroxyvitamin D3 (1,25D) production and hypophosphatemia. Bones from mice with XLH (Hyp) have enlarged osteocyte lacunae, enhanced osteocyte expression of genes of bone remodeling, and impaired canalicular structure. The altered lacuno-canalicular (LCN) phenotype is improved with 1,25D or anti-FGF23 antibody treatment, pointing to roles for 1,25D and/or phosphate in regulating this process. To address whether impaired 1,25D action results in LCN alterations, the LCN phenotype was characterized in mice lacking the vitamin D receptor (VDR) in osteocytes (VDRf/f;DMP1Cre+). Mice lacking the sodium phosphate transporter NPT2a (NPT2aKO) have hypophosphatemia and high serum 1,25D levels, therefore the LCN phenotype was characterized in these mice to determine if increased 1,25D compensates for hypophosphatemia in regulating LCN remodeling. Unlike Hyp mice, neither VDRf/f;DMP1Cre+ nor NPT2aKO mice have dramatic alterations in cortical microarchitecture, allowing for dissecting 1,25D and phosphate specific effects on LCN remodeling in tibial cortices. Histomorphometric analyses demonstrate that, like Hyp mice, tibiae and calvariae in VDRf/f;DMP1Cre+ and NPT2aKO mice have enlarged osteocyte lacunae (tibiae: 0.15±0.02μm2(VDRf/f;DMP1Cre-) vs 0.19±0.02μm2(VDRf/f;DMP1Cre+), 0.12±0.02μm2(WT) vs 0.18±0.0μm2(NPT2aKO), calvariae: 0.09±0.02μm2(VDRf/f;DMP1Cre-) vs 0.11±0.02μm2(VDRf/f;DMP1Cre+), 0.08±0.02μm2(WT) vs 0.13±0.02μm2(NPT2aKO), p<0.05 all comparisons) and increased immunoreactivity of bone resorption marker Cathepsin K (Ctsk). The osteocyte enriched RNA isolated from tibiae in VDRf/f;DMP1Cre+ and NPT2aKO mice have enhanced expression of matrix resorption genes that are classically expressed by osteoclasts (Ctsk, Acp5, Atp6v0d2, Nhedc2). Treatment of Ocy454 osteocytes with 1,25D or phosphate inhibits the expression of these genes. Like Hyp mice, VDRf/f;DMP1Cre+ and NPT2aKO mice have impaired canalicular organization in tibia and calvaria. These studies demonstrate that hypophosphatemia and osteocyte-specific 1,25D actions regulate LCN remodeling. Impaired 1,25D action and low phosphate levels contribute to the abnormal LCN phenotype observed in XLH.
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Affiliation(s)
- Ye Yuan
- Harvard Medical School, Boston, Massachusetts, United States of America
- Division of Endocrinology, Diabetes, Hypertension, Brigham and Women’s Hospital, Boston, Massachusetts, United States of America
| | - Supriya Jagga
- Harvard Medical School, Boston, Massachusetts, United States of America
- Division of Endocrinology, Diabetes, Hypertension, Brigham and Women’s Hospital, Boston, Massachusetts, United States of America
| | - Janaina S. Martins
- Harvard Medical School, Boston, Massachusetts, United States of America
- Endocrine Unit, Massachusetts General Hospital, Boston, Massachusetts, United States of America
| | - Rakshya Rana
- Division of Endocrinology, Diabetes, Hypertension, Brigham and Women’s Hospital, Boston, Massachusetts, United States of America
| | - Paola Divieti Pajevic
- Department of Translational Dental Medicine, Boston University School of Dental Medicine, Boston, Massachusetts, United States of America
| | - Eva S. Liu
- Harvard Medical School, Boston, Massachusetts, United States of America
- Division of Endocrinology, Diabetes, Hypertension, Brigham and Women’s Hospital, Boston, Massachusetts, United States of America
- * E-mail:
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155
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Constantacos C, Hunter JD, Walsh ET, South AM. Rare PHEX variant with insidious presentation leads to a delayed diagnosis of X-linked hypophosphatemia. BMJ Case Rep 2021; 14:14/5/e240336. [PMID: 34011663 DOI: 10.1136/bcr-2020-240336] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
A 7-year-old girl without a significant previous medical history was diagnosed with X-linked hypophosphatemic rickets (XLHR) due to a rare, most likely pathogenic, PHEX gene variant after a 4-year delayed diagnosis due to mild clinical presentation. At 2 years of age, her intoeing and femoral bowing were attributed to physiologic bowing and borderline vitamin D sufficiency, despite phosphorus not being measured. Hypophosphatemia was eventually detected after incomplete improvement of bowing and leg length discrepancy with suboptimal linear growth. This rare PHEX variant (c.1949T>C, p.Leu650Pro) further supported the clinical diagnosis of XLHR. Treatment with burosumab (an anti-FGF23 monoclonal antibody) normalised phosphorus and alkaline phosphatase levels and improved her bowing. The diverse phenotypic presentation of this variant can result in delayed diagnosis and highlights the importance of prompt assessment of phosphorus levels in patients with skeletal deformities to ensure timely recognition and treatment.
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Affiliation(s)
- Cathrine Constantacos
- Pediatrics, Section of Endocrinology, Wake Forest University School of Medicine, Winston Salem, North Carolina, USA
| | - Janel Darcy Hunter
- Pediatrics, Section of Endocrinology, Wake Forest University School of Medicine, Winston Salem, North Carolina, USA
| | - Elizabeth Tharpe Walsh
- Pediatrics, Section of Endocrinology, Wake Forest University School of Medicine, Winston Salem, North Carolina, USA
| | - Andrew Michael South
- Pediatrics, Section of Nephrology, Wake Forest University School of Medicine, Winston Salem, North Carolina, USA.,Epidemiology and Prevention, Division of Public Health Sciences, Wake Forest University School of Medicine, Winston Salem, North Carolina, USA
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156
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Papadopoulou A, Bountouvi E, Karachaliou FE. The Molecular Basis of Calcium and Phosphorus Inherited Metabolic Disorders. Genes (Basel) 2021; 12:genes12050734. [PMID: 34068220 PMCID: PMC8153134 DOI: 10.3390/genes12050734] [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: 02/15/2021] [Revised: 04/30/2021] [Accepted: 05/05/2021] [Indexed: 02/07/2023] Open
Abstract
Calcium (Ca) and Phosphorus (P) hold a leading part in many skeletal and extra-skeletal biological processes. Their tight normal range in serum mirrors their critical role in human well-being. The signalling “voyage” starts at Calcium Sensing Receptor (CaSR) localized on the surface of the parathyroid glands, which captures the “oscillations” of extracellular ionized Ca and transfers the signal downstream. Parathyroid hormone (PTH), Vitamin D, Fibroblast Growth Factor (FGF23) and other receptors or ion-transporters, work synergistically and establish a highly regulated signalling circuit between the bone, kidneys, and intestine to ensure the maintenance of Ca and P homeostasis. Any deviation from this well-orchestrated scheme may result in mild or severe pathologies expressed by biochemical and/or clinical features. Inherited disorders of Ca and P metabolism are rare. However, delayed diagnosis or misdiagnosis may cost patient’s quality of life or even life expectancy. Unravelling the thread of the molecular pathways involving Ca and P signaling, we can better understand the link between genetic alterations and biochemical and/or clinical phenotypes and help in diagnosis and early therapeutic intervention.
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157
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Padidela R, Whyte MP, Glorieux FH, Munns CF, Ward LM, Nilsson O, Portale AA, Simmons JH, Namba N, Cheong HI, Pitukcheewanont P, Sochett E, Högler W, Muroya K, Tanaka H, Gottesman GS, Biggin A, Perwad F, Williams A, Nixon A, Sun W, Chen A, Skrinar A, Imel EA. Patient-Reported Outcomes from a Randomized, Active-Controlled, Open-Label, Phase 3 Trial of Burosumab Versus Conventional Therapy in Children with X-Linked Hypophosphatemia. Calcif Tissue Int 2021; 108:622-633. [PMID: 33484279 PMCID: PMC8064984 DOI: 10.1007/s00223-020-00797-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Accepted: 12/14/2020] [Indexed: 12/11/2022]
Abstract
Changing to burosumab, a monoclonal antibody targeting fibroblast growth factor 23, significantly improved phosphorus homeostasis, rickets, lower-extremity deformities, mobility, and growth versus continuing oral phosphate and active vitamin D (conventional therapy) in a randomized, open-label, phase 3 trial involving children aged 1-12 years with X-linked hypophosphatemia. Patients were randomized (1:1) to subcutaneous burosumab or to continue conventional therapy. We present patient-reported outcomes (PROs) from this trial for children aged ≥ 5 years at screening (n = 35), using a Patient-Reported Outcomes Measurement Information System (PROMIS) questionnaire and SF-10 Health Survey for Children. PROMIS pain interference, physical function mobility, and fatigue scores improved from baseline with burosumab at weeks 40 and 64, but changed little with continued conventional therapy. Pain interference scores differed significantly between groups at week 40 (- 5.02, 95% CI - 9.29 to - 0.75; p = 0.0212) but not at week 64. Between-group differences were not significant at either week for physical function mobility or fatigue. Reductions in PROMIS pain interference and fatigue scores from baseline were clinically meaningful with burosumab at weeks 40 and 64 but not with conventional therapy. SF-10 physical health scores (PHS-10) improved significantly with burosumab at week 40 (least-squares mean [standard error] + 5.98 [1.79]; p = 0.0008) and week 64 (+ 5.93 [1.88]; p = 0.0016) but not with conventional therapy (between-treatment differences were nonsignificant). In conclusion, changing to burosumab improved PRO measures, with statistically significant differences in PROMIS pain interference at week 40 versus continuing with conventional therapy and in PHS-10 at weeks 40 and 64 versus baseline.Trial registration: ClinicalTrials.gov NCT02915705.
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Affiliation(s)
- Raja Padidela
- Department of Paediatric Endocrinology, Royal Manchester Children's Hospital, Manchester, UK.
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK.
| | - Michael P Whyte
- Shriners Hospitals for Children -Washington University School of Medicine in St Louis, St Louis, MO, USA
| | - Francis H Glorieux
- Shriners Hospital for Children - Canada, McGill University, Montreal, QC, Canada
| | - Craig F Munns
- The University of Sydney Children's Hospital Westmead Clinical School, The Children's Hospital at Westmead, Westmead, NSW, Australia
- Department of Endocrinology, The Children's Hospital at Westmead, Westmead, NSW, Australia
| | - Leanne M Ward
- Department of Pediatrics, University of Ottawa, Ottawa, ON, Canada
- Division of Endocrinology and Metabolism, Children's Hospital of Eastern Ontario, Ottawa, ON, Canada
| | - Ola Nilsson
- Division of Pediatric Endocrinology & Center for Molecular Medicine, Karolinska Institute, Stockholm, Sweden
- School of Medical Sciences, Örebro University, Örebro, Sweden
| | - Anthony A Portale
- Department of Pediatrics, University of California, San Francisco, San Francisco, CA, USA
| | - Jill H Simmons
- Departments of Pediatrics, Division of Endocrinology and Diabetes, Vanderbilt University School of Medicine, Vanderbilt University, Nashville, TN, USA
| | - Noriyuki Namba
- Department of Pediatrics, Osaka Hospital, Japan Community Healthcare Organization, Osaka, Japan
- Department of Pediatrics, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Hae Il Cheong
- Seoul National University Children's Hospital, Seoul, Republic of Korea
| | - Pisit Pitukcheewanont
- Center of Endocrinology, Diabetes and Metabolism, Children's Hospital Los Angeles, Los Angeles, CA, USA
| | - Etienne Sochett
- Department of Paediatrics, Hospital for Sick Children, Toronto, ON, Canada
| | - Wolfgang Högler
- Department of Paediatrics and Adolescent Medicine, Johannes Kepler University Linz, Linz, Austria
- Institute of Metabolism and Systems Research, University of Birmingham, Birmingham, UK
| | - Koji Muroya
- Department of Endocrinology and Metabolism, Kanagawa Children's Medical Center, Yokohama, Japan
| | - Hiroyuki Tanaka
- Okayama Saiseikai General Hospital Outpatient Center, Okayama, Japan
| | | | - Andrew Biggin
- The University of Sydney Children's Hospital Westmead Clinical School, The Children's Hospital at Westmead, Westmead, NSW, Australia
| | - Farzana Perwad
- Department of Pediatrics, University of California, San Francisco, San Francisco, CA, USA
| | | | | | - Wei Sun
- Kyowa Kirin Pharmaceutical Development, Princeton, NJ, USA
| | - Angel Chen
- Ultragenyx Pharmaceutical, Novato, CA, USA
| | | | - Erik A Imel
- Department of Medicine and Department of Pediatrics, Indiana University School of Medicine, Indianapolis, IN, USA
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158
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Kalantar‐Zadeh K, Ganz T, Trumbo H, Seid MH, Goodnough LT, Levine MA. Parenteral iron therapy and phosphorus homeostasis: A review. Am J Hematol 2021; 96:606-616. [PMID: 33471363 PMCID: PMC8248123 DOI: 10.1002/ajh.26100] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 01/13/2021] [Accepted: 01/17/2021] [Indexed: 12/16/2022]
Abstract
Phosphorus has an essential role in cellular and extracellular metabolism; maintenance of normal phosphorus homeostasis is critical. Phosphorus homeostasis can be affected by diet and certain medications; some intravenous iron formulations can induce renal phosphate excretion and hypophosphatemia, likely through increasing serum concentrations of intact fibroblast growth factor 23. Case studies provide insights into two types of hypophosphatemia: acute symptomatic and chronic hypophosphatemia, while considering the role of pre‐existing conditions and comorbidities, medications, and intravenous iron. This review examines phosphorus homeostasis and hypophosphatemia, with emphasis on effects of iron deficiency and iron replacement using intravenous iron formulations.
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Affiliation(s)
- Kamyar Kalantar‐Zadeh
- Division of Nephrology and Hypertension and Kidney Transplantation University of California Irvine Orange California USA
| | - Tomas Ganz
- David Geffen School of Medicine University of California, Los Angeles Los Angeles California USA
| | - Henry Trumbo
- St. Mary Medical Center Langhorne Pennsylvania USA
| | - Melvin H. Seid
- Department of Obstetrics and Gynecology University of Southern California Verdugo Hills Hospital Glendale California USA
| | | | - Michael A. Levine
- Center for Bone Health and Division of Endocrinology and Diabetes Children's Hospital of Philadelphia and University of Pennsylvania Perelman School of Medicine Philadelphia Pennsylvania USA
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159
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Lira Dos Santos EJ, Chavez MB, Tan MH, Mohamed FF, Kolli TN, Foster BL, Liu ES. Effects of Active Vitamin D or FGF23 Antibody on Hyp Mice Dentoalveolar Tissues. J Dent Res 2021; 100:1482-1491. [PMID: 33906518 DOI: 10.1177/00220345211011041] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Mutations in the PHEX gene lead to X-linked hypophosphatemia (XLH), a form of inherited rickets featuring elevated fibroblast growth factor 23 (FGF23), reduced 1,25-dihydroxyvitamin D (1,25D), and hypophosphatemia. Hyp mutant mice replicate the XLH phenotype, including dentin, alveolar bone, and cementum defects. We aimed to compare effects of 1,25D versus FGF23-neutralizing antibody (FGF23Ab) monotherapies on Hyp mouse dentoalveolar mineralization. Male Hyp mice, either injected subcutaneously with daily 1,25D or thrice weekly with FGF23 blocking antibody from 2 to 35 d postnatal, were compared to wild-type (WT) controls and untreated Hyp mice. Mandibles were analyzed by high-resolution micro-computed tomography (micro-CT), histology, and immunohistochemistry. Both interventions maintained normocalcemia, increased serum phosphate levels, and improved dentoalveolar mineralization in treated versus untreated Hyp mice. 1,25D increased crown dentin volume and thickness and root dentin/cementum volume, whereas FGF23Ab effects were limited to crown dentin volume. 1,25D increased bone volume fraction, bone mineral density, and tissue mineral density in Hyp mice, whereas FGF23Ab failed to significantly affect these alveolar bone parameters. Neither treatment fully attenuated dentin and bone defects to WT levels, and pulp volumes remained elevated regardless of treatment. Both treatments reduced predentin thickness and improved periodontal ligament organization, while 1,25D promoted a more profound improvement in acellular cementum thickness. Altered cell densities and lacunocanalicular properties of alveolar and mandibular bone osteocytes and cementocytes in Hyp mice were partially corrected by either treatment. Neither treatment normalized the altered distributions of bone sialoprotein and osteopontin in Hyp mouse alveolar bone. Moderate improvements from both 1,25D and FGF23Ab treatment regimens support further studies and collection of oral health data from subjects receiving a newly approved anti-FGF23 therapy. The inability of either treatment to fully correct Hyp mouse dentin and bone prompts further experiments into underlying pathological mechanisms to identify new therapeutic approaches.
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Affiliation(s)
- E J Lira Dos Santos
- Biosciences Division, College of Dentistry, The Ohio State University, Columbus, OH, USA.,Campinas State University, School of Dentistry, Piracicaba, São Paulo, Brazil
| | - M B Chavez
- Biosciences Division, College of Dentistry, The Ohio State University, Columbus, OH, USA
| | - M H Tan
- Biosciences Division, College of Dentistry, The Ohio State University, Columbus, OH, USA
| | - F F Mohamed
- Biosciences Division, College of Dentistry, The Ohio State University, Columbus, OH, USA
| | - T N Kolli
- Biosciences Division, College of Dentistry, The Ohio State University, Columbus, OH, USA
| | - B L Foster
- Biosciences Division, College of Dentistry, The Ohio State University, Columbus, OH, USA
| | - E S Liu
- Endocrine Unit, Massachusetts General Hospital, Boston, MA, USA.,Division of Endocrinology Diabetes and Hypertension, Brigham and Women's Hospital, Boston, MA, USA.,Harvard Medical School, Boston, MA, USA
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160
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Cheung M, Rylands AJ, Williams A, Bailey K, Bubbear J. Patient-Reported Complications, Symptoms, and Experiences of Living With X-Linked Hypophosphatemia Across the Life-Course. J Endocr Soc 2021; 5:bvab070. [PMID: 34258488 PMCID: PMC8272533 DOI: 10.1210/jendso/bvab070] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Indexed: 11/19/2022] Open
Abstract
Context X-linked hypophosphatemia (XLH) is a rare, genetic phosphate-wasting disease resulting in bone, muscular, and dental problems, beginning in childhood and increasing in adulthood. Objective This qualitative analysis aimed to explore patient-reported symptoms, complications, and experiences of XLH over the life-course, using data from a large multinational online survey. Methods Responses to 2 open-ended questions from 209 adults and 86 children/adolescents (proxy report) with self-reported XLH were analyzed in 8 age groups. Two researchers independently coded and analyzed the responses, using thematic analysis, with differences settled among a multidisciplinary group. Six themes were identified, with age subgroup analysis conducted on the 3 most common, according to coding frequency. Results Within theme 1, “Clinical Signs and Symptoms of XLH,” “Pain” was a dominant subtheme across the life-course, but “Skeletal Pathology” dominated the responses of children/adolescents. Within theme 2, “Impacts of Clinical Signs and Symptoms,” interference with “Physical Exertion” and “Emotional Wellbeing” (comprising depression/anxiety in adults and lack of self-esteem in children/adolescents) was reported across all ages. For theme 3, “Negative Treatment Experiences,” “Medication” was problematic for children, with adults reporting lack of “Access to Appropriate Treatment.” Three further themes were identified: “Resilience,” “Positive Treatment Experiences,” and “Information Needs.” Conclusion The multiple burdens imposed on people with XLH throughout their lifetime encompassed the physical, emotional, and social, although the most challenging symptoms or complications differed between ages. Burden was further exacerbated by adults’ lack of access to appropriate treatment, illustrating the need for age-appropriate multidisciplinary care.
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Affiliation(s)
- Moira Cheung
- Evelina London Children's Hospital, London, SE1 7EH, UK
| | - Angela J Rylands
- Kyowa Kirin International, Galashiels, Selkirkshire, TD1 1QH, UK
| | - Angela Williams
- Kyowa Kirin International, Galashiels, Selkirkshire, TD1 1QH, UK
| | | | - Judith Bubbear
- Royal National Orthopaedic Hospital NHS Trust, Middlesex, HA7 4LP, UK
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161
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Baroncelli GI, Zampollo E, Manca M, Toschi B, Bertelloni S, Michelucci A, Isola A, Bulleri A, Peroni D, Giuca MR. Pulp chamber features, prevalence of abscesses, disease severity, and PHEX mutation in X-linked hypophosphatemic rickets. J Bone Miner Metab 2021; 39:212-223. [PMID: 32772199 DOI: 10.1007/s00774-020-01136-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Accepted: 07/27/2020] [Indexed: 02/07/2023]
Abstract
INTRODUCTION Rickets, growth failure, and recurrent periapical abscesses with fistulae are main signs in patients with X-linked hypophosphatemic rickets (XLH). Prevalence of abscesses, pulp chamber features, biochemical findings, disease severity, and PHEX gene mutation were examined. MATERIALS AND METHODS Pulp chambers size, shape, and morphology were assessed by orthopantomography in XLH patients (n = 24, age 5.8 ± 1.6 years) and in sex and age-matched healthy controls (n = 23, age 6.2 ± 1.4 years). XLH patients received conventional treatment (3.5 ± 1.9 years). Pulp chamber features were assessed in teeth of primary dentition and in the permanent left mandibular first molar and compared with those of controls. Rickets severity score was assessed at wrist, knee, and ankle. RESULTS The mean pulp chamber area/tooth area ratio, mean pulp chamber height/pulp chamber width ratio, and prominence of pulp horns into the tooth crown in primary and secondary molars were significantly higher in patients than in controls and in patients suffered abscesses than in patients without abscesses. Sixteen patients (67%) had a history of abscesses; incisors were affected more than canines and molars. Severity of rickets and mean serum parathyroid hormone (PTH) levels were significantly higher, and mean serum 1,25-dihydroxyvitamin D [1,25(OH)2D] levels significantly lower in patients suffered abscesses than in patients without abscesses. PHEX gene mutations were not correlated with dental phenotype and disease severity. CONCLUSION Enlarged pulp chambers with altered shape and morphology affected the majority of XLH patients predisposing to recurrent periapical abscesses with fistulae. Dental phenotype was associated with severity of rickets, high serum PTH, and low serum 1,25(OH)2D levels.
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Affiliation(s)
- Giampiero I Baroncelli
- Division of Pediatrics, Endocrine Unit, Department of Obstetrics, Gynecology and Pediatrics, University-Hospital, Via Roma 67, 56126, Pisa, Italy.
| | - Elisa Zampollo
- Division of Dentistry and Oral Surgery, Department of Surgical Specialties, University-Hospital, Pisa, Italy
| | - Mario Manca
- Unit of Orthopedics, Usl Northwest-Tuscany, Versilia Hospital, Camaiore, Italy
| | - Benedetta Toschi
- Division of Medical Genetics, Department of Medical and Oncological Area, University-Hospital, Pisa, Italy
| | - Silvano Bertelloni
- Division of Pediatrics, Endocrine Unit, Department of Obstetrics, Gynecology and Pediatrics, University-Hospital, Via Roma 67, 56126, Pisa, Italy
| | - Angela Michelucci
- Unit of Molecular Genetics, Department of Laboratory Medicine, University-Hospital, Pisa, Italy
| | - Alessandro Isola
- Unit of Orthopedics, Usl Northwest-Tuscany, Versilia Hospital, Camaiore, Italy
| | - Alessandra Bulleri
- Unit of Radiodiagnostic, Department of Diagnostic Imaging, University-Hospital, Pisa, Italy
| | - Diego Peroni
- Division of Pediatrics, Endocrine Unit, Department of Obstetrics, Gynecology and Pediatrics, University-Hospital, Via Roma 67, 56126, Pisa, Italy
| | - Maria Rita Giuca
- Division of Dentistry and Oral Surgery, Department of Surgical Specialties, University-Hospital, Pisa, Italy
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Rodríguez-Rubio E, Gil-Peña H, Chocron S, Madariaga L, de la Cerda-Ojeda F, Fernández-Fernández M, de Lucas-Collantes C, Gil M, Luis-Yanes MI, Vergara I, González-Rodríguez JD, Ferrando S, Antón-Gamero M, Carrasco Hidalgo-Barquero M, Fernández-Escribano A, Fernández-Maseda MÁ, Espinosa L, Oliet A, Vicente A, Ariceta G, Santos F. Phenotypic characterization of X-linked hypophosphatemia in pediatric Spanish population. Orphanet J Rare Dis 2021; 16:104. [PMID: 33639975 PMCID: PMC7912818 DOI: 10.1186/s13023-021-01729-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Accepted: 02/03/2021] [Indexed: 11/26/2022] Open
Abstract
Background X-linked hypophosphatemia (XLH) is a hereditary rare disease caused by loss-of-function mutations in PHEX gene leading tohypophosphatemia and high renal loss of phosphate. Rickets and growth retardation are the major manifestations of XLH in children, but there is a broad phenotypic variability. Few publications have reported large series of patients. Current data on the clinical spectrum of the disease, the correlation with the underlying gene mutations, and the long-term outcome of patients on conventional treatment are needed, particularly because of the recent availability of new specific medications to treat XLH. Results The RenalTube database was used to retrospectively analyze 48 Spanish patients (15 men) from 39 different families, ranging from 3 months to 8 years and 2 months of age at the time of diagnosis (median age of 2.0 years), and with XLH confirmed by genetic analysis. Bone deformities, radiological signs of active rickets and growth retardation were the most common findings at diagnosis. Mean (± SEM) height was − 1.89 ± 0.19 SDS and 55% (22/40) of patients had height SDS below—2. All cases had hypophosphatemia, serum phosphate being − 2.81 ± 0.11 SDS. Clinical manifestations and severity of the disease were similar in both genders. No genotype—phenotype correlation was found. Conventional treatment did not attenuate growth retardation after a median follow up of 7.42 years (IQR = 11.26; n = 26 patients) and failed to normalize serum concentrations of phosphate. Eleven patients had mild hyperparathyroidism and 8 patients nephrocalcinosis. Conclusions This study shows that growth retardation and rickets were the most prevalent clinical manifestations at diagnosis in a large series of Spanish pediatric patients with XLH confirmed by mutations in the PHEX gene. Traditional treatment with phosphate and vitamin D supplements did not improve height or corrected hypophosphatemia and was associated with a risk of hyperparathyroidism and nephrocalcinosis. The severity of the disease was similar in males and females.
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Affiliation(s)
| | - Helena Gil-Peña
- AGC Pediatría, Hospital Universitario Central de Asturias, Oviedo, Spain
| | - Sara Chocron
- Servicio de Nefrología Pediátrica, Hospital Vall D'Hebron, Universitat Autónoma de Barcelona, Barcelona, Spain
| | - Leire Madariaga
- Servicio Nefrología Pediátrica, IIS Biocruces-Bizkaia, Universidad del País Vasco UPV/EHU, Hospital Universitario Cruces, Barakaldo, Spain
| | | | | | | | - Marta Gil
- Servicio Pediatría, Hospital Universitario de Santiago de Compostela, Santiago de Compostela, Spain
| | - María Isabel Luis-Yanes
- Servicio Pediatría, Hospital Universitario Nuestra Señora de Candelaria, Santa Cruz de Tenerife, Spain
| | - Inés Vergara
- Servicio Pediatría, Complexo Hospitalario Universitario A Coruña (CHUAC), A Coruña, Spain
| | | | - Susana Ferrando
- Servicio de Pediatría, Hospital Clínico Universitario de Valencia, Valencia, Spain
| | | | | | | | | | - Laura Espinosa
- Servicio Nefrología infantile, Hospital Universitario Infantil La Paz, Madrid, Spain
| | - Aniana Oliet
- Servicio Nefrología, Hospital Severo Ochoa, Leganés, Spain
| | | | - Gema Ariceta
- Servicio de Nefrología Pediátrica, Hospital Vall D'Hebron, Universitat Autónoma de Barcelona, Barcelona, Spain
| | - Fernando Santos
- Pediatric Research, Medicine Department, University of Oviedo, Oviedo, Spain.,AGC Pediatría, Hospital Universitario Central de Asturias, Oviedo, Spain
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Broseta JJ. Different approaches to improve cohort identification using electronic health records: X-linked hypophosphatemia as an example. Intractable Rare Dis Res 2021; 10:17-22. [PMID: 33614371 PMCID: PMC7882088 DOI: 10.5582/irdr.2020.03123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
Electronic Health Records (EHRs) represent a source of high value data which is often underutilized because exploiting the information contained therein requires specialized techniques unavailable to the end user i.e. the physician or the investigator. Here I describe four simple and practical avenues that will allow the standard EHR end user to identify patient cohorts: the use of diagnostic codes from different international catalogues; a search in reports from complementary tests (e.g. radiographs or lab tests) for any result of interest; a free text search; or a drug prescription search in the patient's electronic prescription record. This medical approach is acquiring great importance in the field of rare diseases, and here I demonstrate its application with X-linked hypophosphatemia. The use of these four EHR questioning approaches makes finding a cohort of patients of any condition or disease feasible and manageable, and once each case record is checked, a well-defined cohort can be assembled.
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Affiliation(s)
- Jose Jesus Broseta
- Department of Nephrology and Renal Transplantation, Hospital Clínic of Barcelona, Barcelona, Spain
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164
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McKenna MJ, Crowley RK, Twomey PJ, Kilbane MT. Renal Phosphate Handling: Independent Effects of Circulating FGF23, PTH, and Calcium. JBMR Plus 2021; 5:e10437. [PMID: 33615106 PMCID: PMC7872336 DOI: 10.1002/jbm4.10437] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Accepted: 11/13/2020] [Indexed: 12/25/2022] Open
Abstract
Excess fibroblast growth factor 23 (FGF23), excess PTH, and an increase in extracellular calcium cause hypophosphatemia by lowering the maximum renal phosphate reabsorption threshold (TmP/GFR). We recently reported two cases of X-linked hypophosphatemia (XLH) with severe tertiary hyperparathyroidism who had normalization of TmP/GFR upon being rendered hypoparathyroid following total parathyroidectomy, despite marked excess in both C-terminal FGF23 (cFGF23) and intact FGF23 (iFGF23). We explored the effects of FGF23, PTH, and calcium on TmP/GFR in a cross-sectional study (n = 74) across a spectrum of clinical cases with abnormalities in TmP/GFR, PTH, and FGF23. This comprised three groups: FGF23-dependent hypophosphatemia (n = 27), hypoparathyroidism (HOPT; n = 17), and chronic kidney disease (n = 30). Measurements included TmP/GFR, cFGF23, PTH, ionized calcium, vitamin D metabolites, and bone turnover markers. The combined effect of cFGF23, PTH, and ionized calcium on TmP/GFR was modeled using hierarchical multiple regression and was probed by moderation analysis with PROCESS. Modeling analysis showed independent effects on TmP/GFR by cFGF23, PTH, and ionized calcium in conjunction with a weak but significant effect of the interaction term for PTH and FGF23; probing showed that the effect was most prominent during PTH deficiency. Teriparatide 20 μg daily was self-administered for 28 days by one case of X-linked hypophosphatemia with hypoparathyroidism (XLH-HOPT) to assess the response of TmP/GFR, cFGF23, iFGF23, nephrogenous cyclic adenosine monophosphate (NcAMP), vitamin D metabolites, and bone turnover markers. After 28 days, TmP/GFR was lowered from 1.10 mmol/L to 0.48 mmol/L; this was accompanied by increases in NcAMP, ionized calcium, and bone turnover markers. In conclusion, the effect of FGF23 excess on TmP/GFR is altered by PTH such that the effect is ameliorated by hypoparathyroidism and the effect is augmented by hyperparathyroidism. © 2020 The Authors. JBMR Plus published by Wiley Periodicals LLC. on behalf of American Society for Bone and Mineral Research.
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Affiliation(s)
- Malachi J McKenna
- UCD School of MedicineUniversity College DublinDublinIreland
- Department of Clinical ChemistrySt. Vincent's University HospitalDublinIreland
- Department of EndocrinologySt. Vincent's University HospitalDublinIreland
| | - Rachel K Crowley
- UCD School of MedicineUniversity College DublinDublinIreland
- Department of Clinical ChemistrySt. Vincent's University HospitalDublinIreland
- Department of EndocrinologySt. Vincent's University HospitalDublinIreland
| | - Patrick J Twomey
- UCD School of MedicineUniversity College DublinDublinIreland
- Department of Clinical ChemistrySt. Vincent's University HospitalDublinIreland
| | - Mark T Kilbane
- UCD School of MedicineUniversity College DublinDublinIreland
- Department of Clinical ChemistrySt. Vincent's University HospitalDublinIreland
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165
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New therapeutic options for bone diseases. Wien Med Wochenschr 2021; 171:120-125. [PMID: 33512621 DOI: 10.1007/s10354-020-00810-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Accepted: 12/28/2020] [Indexed: 02/07/2023]
Abstract
In recent years, new treatment options for both common and rare bone diseases have become available. The sclerostin antibody romosozumab is the most recently approved drug for the therapy of postmenopausal osteoporosis. Its anabolic capacity makes it a promising treatment option for severe osteoporosis. Other sclerostin antibodies for the treatment of rare bone diseases such as osteogenesis imperfecta are currently being investigated. For rare bone diseases such as X‑linked hypophosphatemia (XLH) and hypophosphatasia (HPP), specific therapies are now also available, showing promising data in children and adults with a severe disease course. However, long-term data are needed to assess a sustained benefit for patients.
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166
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Zehra N, Jafri L, Kirmani S, Khan AH. X-linked hypophosphatemic osteomalacia with PHEX mutation presenting late in Pakistan. Ann Med Surg (Lond) 2021; 62:244-248. [PMID: 33537138 PMCID: PMC7840437 DOI: 10.1016/j.amsu.2021.01.067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 01/17/2021] [Accepted: 01/17/2021] [Indexed: 11/17/2022] Open
Abstract
Abstract.introduction.and.importance Autosomal dominant hypophosphatemic rickets is the most common form of rare rickets, commonly manifests in children but sometimes the condition remains undiagnosed due to lack of knowledge &/or awareness of treating physicians or surgeons. Case presentation We describe a case of 43 years old female with multiple fragility fractures since childhood, corrected surgically but never investigated. She had stunted growth, bowing deformities and loss of teeth. Clinical discussion A detailed history and examination along with metabolic and genetic work up mounted the diagnosis of X linked hypophosphatemic osteomalacia. The pathophysiology involves the mutation or the loss of the phosphate regulating gene on PHEX, that causes reduced mineralization of bones and teeth. Conclusion Diagnostic delay in this patient resulted in increased disabilities affecting her mobility and lif estyle. Rickets represents diseases of divergent causes, characterized by defect in matrix mineralization. Hypophosphatemic rickets is the most common form of autosomal dominant rickets. It involves the PHEX mutation. Awareness of these disorders among clinicians remains a diagnostic challenge because of their rarity and wide variety.
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Affiliation(s)
- Nawazish Zehra
- Department of Pathology and Laboratory Medicine, Pakistan
| | - Lena Jafri
- Department of Pathology and Laboratory Medicine, Pakistan
| | - Salman Kirmani
- Department of Pediatric and Child Health Aga Khan University, Karachi, Pakistan
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167
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Marcucci G, Brandi ML. Congenital Conditions of Hypophosphatemia Expressed in Adults. Calcif Tissue Int 2021; 108:91-103. [PMID: 32409880 DOI: 10.1007/s00223-020-00695-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Accepted: 04/15/2020] [Indexed: 01/05/2023]
Abstract
The main congenital conditions of hypophosphatemia expressed in adulthood include several forms of hereditary hypophosphatemic rickets and a congenital disorder of vitamin D metabolism characterized by osteomalacia and hypophosphatemia in adult patients. Hypophosphatemia in adults is defined as serum phosphate concentration < 0.80 mmol/L. The principal regulators of phosphate homeostasis, as is well known, are parathyroid hormone (PTH), activated vitamin D, and Fibroblast Growth Factor 23 (FGF23). Differential diagnosis of hypophosphatemia is based on the evaluation of mechanisms leading to this alteration, such as high PTH activity, inadequate phosphate absorption from the gut, or renal phosphate wasting, either due to primary tubular defects or high FGF23 levels. The most common inherited form associated to hypophosphatemia is X-linked hypophosphatemic rickets (XLH), caused by PHEX gene mutations with enhanced secretion of the FGF23. Until now, the management of hypophosphatemia in adulthood has been poorly investigated. It is widely debated whether adult patients benefit from the conventional treatments normally used for pediatric patients. The new treatment for XLH with burosumab, a recombinant human IgG1 monoclonal antibody that binds to FGF23, blocking its activity, may change the pharmacological management of adult subjects with hypophosphatemia associated to FGF23-dependent mechanisms.
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Affiliation(s)
- Gemma Marcucci
- Bone Metabolic Diseases Unit, Department of Biomedical, Experimental and Clinical Sciences, University of Florence, AOU Careggi, Florence, Italy
| | - Maria Luisa Brandi
- Bone Metabolic Diseases Unit, Department of Biomedical, Experimental and Clinical Sciences, University of Florence, AOU Careggi, Florence, Italy.
- Head Bone Metabolic Diseases Unit, Department of Biomedical, Experimental and Clinical Sciences, University of Florence, Largo Palagi 1, 50139, Florence, Italy.
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168
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Diagnosis and management of X-linked hypophosphatemia in children and adolescent in the Gulf Cooperation Council countries. Arch Osteoporos 2021; 16:52. [PMID: 33660084 PMCID: PMC7929956 DOI: 10.1007/s11657-021-00879-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Accepted: 01/04/2021] [Indexed: 02/03/2023]
Abstract
INTRODUCTION X-linked hypophosphatemia (XLH) is a rare inherited cause of hypophosphatemic rickets and osteomalacia. It is caused by mutations in the phosphate-regulating endopeptidase homolog, X-linked (PHEX). This results in increased plasma fibroblast growth factor-23 (FGF23), which leads to loss of renal sodium-phosphate co-transporter expression leading to chronic renal phosphate excretion. It also leads to low serum 1,25-dihydroxyvitamin D (1,25(OH)2D), resulting in impaired intestinal phosphate absorption. Chronic hypophosphatemia in XLH leads to impaired endochondral mineralization of the growth plates of long bones with bony deformities. XLH in children and adolescents also causes impaired growth, myopathy, bone pain, and dental abscesses. XLH is the most frequent inherited cause of phosphopenic rickets/osteomalacia. Hypophosphatemia is also found in calcipenic rickets/osteomalacia as a result of secondary hyperparathyroidism. Thus, chronic hypophosphatemia is a common etiologic factor in all types of rickets. RESULTS There is considerable overlap between symptoms and signs of phosphopenic and calcipenic rickets/osteomalacia. Wrong diagnosis leads to inappropriate treatment of rickets/osteomalacia. Nutritional rickets and osteomalacia are common in the Gulf Cooperation Council countries which include Saudi Arabia, United Arab Emirates, Kuwait, Qatar, Bahrain, and Oman. Due to high levels of consanguinity in the region, genetic causes of phosphopenic and calcipenic rickets/osteomalacia are also common. CONCLUSION This guideline was developed to provide an approach to the diagnosis of XLH, especially where there is no family history of the disease, and that other related conditions are not mistaken for XLH. We also guide the medical management of XLH with conventional treatment and with burosumab, a recombinant human IgG1 monoclonal antibody to FGF23.
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Laurent MR, De Schepper J, Trouet D, Godefroid N, Boros E, Heinrichs C, Bravenboer B, Velkeniers B, Lammens J, Harvengt P, Cavalier E, Kaux JF, Lombet J, De Waele K, Verroken C, van Hoeck K, Mortier GR, Levtchenko E, Vande Walle J. Consensus Recommendations for the Diagnosis and Management of X-Linked Hypophosphatemia in Belgium. Front Endocrinol (Lausanne) 2021; 12:641543. [PMID: 33815294 PMCID: PMC8018577 DOI: 10.3389/fendo.2021.641543] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Accepted: 02/19/2021] [Indexed: 12/11/2022] Open
Abstract
X-linked hypophosphatemia (XLH) is the most common genetic form of hypophosphatemic rickets and osteomalacia. In this disease, mutations in the PHEX gene lead to elevated levels of the hormone fibroblast growth factor 23 (FGF23), resulting in renal phosphate wasting and impaired skeletal and dental mineralization. Recently, international guidelines for the diagnosis and treatment of this condition have been published. However, more specific recommendations are needed to provide guidance at the national level, considering resource availability and health economic aspects. A national multidisciplinary group of Belgian experts convened to discuss translation of international best available evidence into locally feasible consensus recommendations. Patients with XLH may present to a wide array of primary, secondary and tertiary care physicians, among whom awareness of the disease should be raised. XLH has a very broad differential-diagnosis for which clinical features, biochemical and genetic testing in centers of expertise are recommended. Optimal care requires a multidisciplinary approach, guided by an expert in metabolic bone diseases and involving (according to the individual patient's needs) pediatric and adult medical specialties and paramedical caregivers, including but not limited to general practitioners, dentists, radiologists and orthopedic surgeons. In children with severe or refractory symptoms, FGF23 inhibition using burosumab may provide superior outcomes compared to conventional medical therapy with phosphate supplements and active vitamin D analogues. Burosumab has also demonstrated promising results in adults on certain clinical outcomes such as pseudofractures. In summary, this work outlines recommendations for clinicians and policymakers, with a vision for improving the diagnostic and therapeutic landscape for XLH patients in Belgium.
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Affiliation(s)
- Michaël R. Laurent
- Centre for Metabolic Bone Diseases, University Hospitals Leuven, Leuven, Belgium
- *Correspondence: Michaël R. Laurent,
| | - Jean De Schepper
- Division of Pediatric Endocrinology, KidZ Health Castle, University Hospital Brussels, Vrije Universiteit Brussel (VUB), Brussels, Belgium
- Department of Pediatric Endocrinology, University Hospital Ghent, Ghent, Belgium
| | - Dominique Trouet
- Department of Pediatric Nephrology, Antwerp University Hospital, Antwerp, Belgium
- Laboratory of Experimental Medicine and Pediatrics, University of Antwerp, Antwerp, Belgium
| | - Nathalie Godefroid
- Pediatric Nephrology, Cliniques Universitaires St. Luc (UCL), Brussels, Belgium
| | - Emese Boros
- Paediatric Endocrinology Unit, Hôpital Universitaire des Enfants Reine Fabiola, Université Libre de Bruxelles, Brussels, Belgium
| | - Claudine Heinrichs
- Paediatric Endocrinology Unit, Hôpital Universitaire des Enfants Reine Fabiola, Université Libre de Bruxelles, Brussels, Belgium
| | - Bert Bravenboer
- Department of Endocrinology, University Hospital Brussels, Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Brigitte Velkeniers
- Department of Endocrinology, University Hospital Brussels, Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Johan Lammens
- Department of Orthopaedic Surgery and Department of Development and Regeneration, Prometheus LRD Division of Skeletal Tissue Engineering, KU Leuven - University Hospitals Leuven, Leuven, Belgium
| | - Pol Harvengt
- XLH Belgium, Belgian X-Linked Hypophosphatemic Rickets (XLH) Patient Association, Waterloo, Belgium
| | - Etienne Cavalier
- Department of Clinical Chemistry, University Hospital Center of Liège, University of Liège, Liège, Belgium
| | - Jean-François Kaux
- Physical Medicine, Rehabilitation and Sports Traumatology, University and University Hospital of Liège, Liège, Belgium
| | - Jacques Lombet
- Division of Nephrology, Department of Pediatrics, University Hospital Center of Liège, Liège, Belgium
| | - Kathleen De Waele
- Department of Pediatric Endocrinology, University Hospital Ghent, Ghent, Belgium
| | - Charlotte Verroken
- Unit for Osteoporosis and Metabolic Bone Diseases, Department of Endocrinology and Metabolism, Ghent University Hospital, Ghent, Belgium
| | - Koenraad van Hoeck
- Department of Pediatric Nephrology, Antwerp University Hospital, Antwerp, Belgium
- Laboratory of Experimental Medicine and Pediatrics, University of Antwerp, Antwerp, Belgium
| | - Geert R. Mortier
- Department of Medical Genetics, Antwerp University Hospital and University of Antwerp, Antwerp, Belgium
| | - Elena Levtchenko
- Department of Pediatrics/Pediatric Nephrology, University Hospitals Leuven, Leuven, Belgium
| | - Johan Vande Walle
- Department of Pediatric Nephrology, University Hospital Ghent, Ghent, Belgium
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Seefried L, Smyth M, Keen R, Harvengt P. Burden of disease associated with X-linked hypophosphataemia in adults: a systematic literature review. Osteoporos Int 2021; 32:7-22. [PMID: 32710160 PMCID: PMC7755619 DOI: 10.1007/s00198-020-05548-0] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Accepted: 07/08/2020] [Indexed: 12/30/2022]
Abstract
UNLABELLED This systematic review collated evidence on the burden of XLH in adults. Data captured highlight the substantial ongoing burden of XLH in adulthood and identified unmet needs. Greater awareness and understanding of the impact of XLH in adulthood are needed to improve care and outcomes in adults with XLH. INTRODUCTION X-linked hypophosphataemia (XLH) is a rare metabolic bone disease characterized by renal phosphate wasting and musculoskeletal manifestations. Whilst the disease's impact in children is well documented, information on the effects of this progressive, debilitating condition on adults is lacking. This systematic review aimed to collate existing evidence on the burden of XLH in adulthood to identify unmet needs. METHODS MEDLINE, Embase and Cochrane Library databases and recent congress reports were searched on 19 February 2019 for English-language publications describing the medical, humanistic and socio-economic impact of XLH in adults (≥ 18 years old). In addition, a structured Internet search was conducted. RESULTS Of the 2351 articles identified, 91 met the selection criteria along with 44 congress abstracts. Data show that adults with XLH experience a range of clinical manifestations, particularly skeletal deformities and (pseudo)fractures, along with pain, dental abnormalities and impaired physical function and mobility. XLH in adulthood impacts on quality of life and places limitations on daily activities. The level of healthcare resource utilization among adults with XLH is indicative of substantial socio-economic burden; further research is needed to quantitate the economic impact on the healthcare system, society and patients. Adults with XLH may not receive appropriate care and treatment; a possible explanation for this is a lack of awareness among healthcare professionals. CONCLUSION XLH in adults is associated with considerable disease burden and unmet needs. Forthcoming studies and increased awareness of the impact of XLH in adulthood should help to improve management of XLH in adulthood and patient outcomes.
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Affiliation(s)
- L Seefried
- Orthopedic Institute, König-Ludwig Haus, University of Würzburg, Würzburg, Germany
| | - M Smyth
- Kyowa Kirin International, Galashiels, UK
| | - R Keen
- Royal National Orthopaedic Hospital, Stanmore, UK
| | - P Harvengt
- RVRH-XLH, French association of patients with XLH (a member of the International XLH Alliance), 20 rue Merlin de Thionville, Appt 120, 92150, Suresnes, France.
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Abstract
Great strides over the past few decades have increased our understanding of the pathophysiology of hypophosphatemic disorders. Phosphate is critically important to a variety of physiologic processes, including skeletal growth, development and mineralization, as well as DNA, RNA, phospholipids, and signaling pathways. Consequently, hypophosphatemic disorders have effects on multiple systems, and may cause a variety of nonspecific signs and symptoms. The acute effects of hypophosphatemia include neuromuscular symptoms and compromise. However, the dominant effects of chronic hypophosphatemia are the effects on musculoskeletal function including rickets, osteomalacia and impaired growth during childhood. While the most common causes of chronic hypophosphatemia in children are congenital, some acquired conditions also result in hypophosphatemia during childhood through a variety of mechanisms. Improved understanding of the pathophysiology of these congenital conditions has led to novel therapeutic approaches. This article will review the pathophysiologic causes of congenital hypophosphatemia, their clinical consequences and medical therapy.
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Affiliation(s)
- Erik Allen Imel
- Division of Endocrinology, Departments of Medicine and Pediatrics, Indiana University School of Medicine, 1120 West Michigan Street, Gatch Building Room 365, Indianapolis, IN, 46112, USA.
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Park PG, Lim SH, Lee H, Ahn YH, Cheong HI, Kang HG. Genotype and Phenotype Analysis in X-Linked Hypophosphatemia. Front Pediatr 2021; 9:699767. [PMID: 34434907 PMCID: PMC8382157 DOI: 10.3389/fped.2021.699767] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/24/2021] [Accepted: 07/08/2021] [Indexed: 11/13/2022] Open
Abstract
Background: X-linked hypophosphatemia (XLH) is the most frequent form of hypophosphatemic rickets and is caused by mutations in the PHEX gene. We analyzed genotype-phenotype correlations in XLH patients with proven PHEX mutations. Methods: PHEX mutations were detected in 55 out of 81 patients who clinically presented with hypophosphatemic rickets. The patients were grouped into nontruncating (n = 9) and truncating (n = 46) mutation groups; their initial presentation as well as long-term clinical findings were evaluated according to these groups. Results: Initial findings, including presenting symptoms, onset age, height standard deviation scores (SDS), and laboratory tests, including serum phosphate level and tubular resorption of phosphate, were not significantly different between the two groups (onset age: nontruncating mutation group, 2.0 years, truncating mutation group, 2.2 years; height SDS: nontruncating mutation group, -1.9, truncating mutation group, -1.7; serum phosphate: nontruncating mutation group, 2.5 mg/dL, truncating mutation group, 2.6 mg/dL). However, at their last follow-up, the serum phosphate level was significantly lower in patients with truncating mutations (nontruncating mutation group: 3.2 mg/dl, truncating mutation group: 2.3 mg/dl; P = 0.006). Additionally, 62.5% of patients with truncating mutations developed nephrocalcinosis at their last follow-up, while none of the patients with nontruncating mutations developed nephrocalcinosis (P = 0.015). Orthopedic surgery due to bony deformations was performed significantly more often in patients with truncating mutations (52.3 vs. 10.0%, P = 0.019). Conclusion: Although considerable inconsistency exists regarding the correlation of truncating mutations and their disease phenotype in several other studies, we cautiously suggest that there would be genotype-phenotype correlation in some aspects of disease manifestation after long-term follow-up. This information can be used when consulting patients with confirmed XLH regarding their disease prognosis.
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Affiliation(s)
| | - Seon Hee Lim
- Department of Pediatrics, Uijeongbu Eulji Medical Center, Uijeongbu, South Korea
| | - HyunKyung Lee
- Department of Pediatrics, Kangwon National University Hopsital, Chuncheon, South Korea
| | - Yo Han Ahn
- Department of Pediatrics, Seoul National University College of Medicine, Seoul, South Korea.,Department of Pediatrics, Seoul National University Children's Hospital, Seoul, South Korea.,Kidney Research Institute, Seoul National University Medical Research Center, Seoul, South Korea
| | - Hae Il Cheong
- Department of Pediatrics, Seoul National University College of Medicine, Seoul, South Korea.,Department of Pediatrics, Hallym University Sacred Heart Hospital, Seoul, South Korea
| | - Hee Gyung Kang
- Department of Pediatrics, Seoul National University College of Medicine, Seoul, South Korea.,Department of Pediatrics, Seoul National University Children's Hospital, Seoul, South Korea.,Kidney Research Institute, Seoul National University Medical Research Center, Seoul, South Korea.,Wide River Institute of Immunology, Seoul National University, Hongcheon, South Korea
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173
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Baroncelli GI, Mora S. X-Linked Hypophosphatemic Rickets: Multisystemic Disorder in Children Requiring Multidisciplinary Management. Front Endocrinol (Lausanne) 2021; 12:688309. [PMID: 34421819 PMCID: PMC8378329 DOI: 10.3389/fendo.2021.688309] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Accepted: 06/14/2021] [Indexed: 12/14/2022] Open
Abstract
X-linked hypophosphatemic rickets (XLH) is the commonest inherited form of rickets. It is caused by an impaired regulation of fibroblast growth factor 23 (FGF23) due to a PHEX gene mutation, which leads to reduced tubular reabsorption of phosphate and renal 1α-hydroxylase activity and increased renal 24-hydroxylase activity. Hypophosphatemia associated with renal phosphate wasting, normal serum levels of calcium, parathyroid hormone, and 25-hydroxyvitamin D represents the main biochemical sign in affected patients. Patients with XLH show rickets and osteomalacia, severe deformities of the lower limbs, bone and muscular pain, stunted growth, and reduced quality of life. However, XLH is a multisystemic disorder requiring multidisciplinary approaches in specialized subdisciplines. Severe complications may occur in patients with XLH including craniosynostosis, hearing loss, progressive bone deformities, dental and periodontal recurrent lesions, and psychosocial distress. Moreover, long-term conventional treatment with active vitamin D metabolites and oral inorganic phosphate salts may cause endocrinological complications such as secondary or tertiary hyperparathyroidism, and adverse events in kidney as hypercalciuria, nephrocalcinosis, and nephrolithiasis. However, conventional treatment does not improve phosphate metabolism and it shows poor and slow effects in improving rickets lesions and linear growth. Recently, some trials of treatment with recombinant human IgG1 monoclonal antibody that targets FGF23 (burosumab) showed significant improvement of serum phosphate concentration and renal tubular reabsorption of phosphate that were associated with a rapid healing of radiologic signs of rickets, reduced muscular and osteoarticular pain, and improved physical function, being more effective for the treatment of patients with XLH in comparison with conventional therapy. Therefore, a global management of patients with XLH is strongly recommended and patients should be seen regularly by a multidisciplinary team of experts.
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Affiliation(s)
- Giampiero Igli Baroncelli
- Pediatric and Adolescent Endocrinology, Department of Obstetrics, Gynecology and Pediatrics, University Hospital, Pisa, Italy
- *Correspondence: Giampiero Igli Baroncelli, ; Stefano Mora,
| | - Stefano Mora
- Laboratory of Pediatric Endocrinology and Bone Densitometry Service, IRCCS San Raffaele Scientific Institute, Milan, Italy
- *Correspondence: Giampiero Igli Baroncelli, ; Stefano Mora,
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174
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Athonvarangkul D, Insogna KL. New Therapies for Hypophosphatemia-Related to FGF23 Excess. Calcif Tissue Int 2021; 108:143-157. [PMID: 32504139 DOI: 10.1007/s00223-020-00705-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Accepted: 05/12/2020] [Indexed: 12/12/2022]
Abstract
FGF23 is a hormone produced by osteocytes in response to an elevation in the concentration of extracellular phosphate. Excess production of FGF23 by bone cells, or rarely by tumors, is the hormonal basis for several musculoskeletal syndromes characterized by hypophosphatemia due to renal phosphate wasting. FGF23-dependent chronic hypophosphatemia causes rickets and osteomalacia, as well as other skeletal complications. Genetic disorders of FGF23-mediated hypophosphatemia include X-linked hypophosphatemia (XLH), autosomal dominant hypophosphatemic rickets (ADHR), autosomal recessive hypophosphatemic rickets (ARHR), fibrous dysplasia of bone, McCune-Albright syndrome, and epidermal nevus syndrome (ENS), also known as cutaneous skeletal hypophosphatemia syndrome (CSHS). The principle acquired form of FGF23-mediated hypophosphatemia is tumor-induced osteomalacia (TIO). This review summarizes current knowledge about the pathophysiology and clinical presentation of the most common FGF23-mediated conditions, with a focus on new treatment modalities. For many decades, calcitriol and phosphate supplements were the mainstay of therapy. Recently, burosumab, a monoclonal blocking antibody to FGF23, has been approved for treatment of XLH in children and adults, and an active comparator trial in children has shown good efficacy and safety for this drug. The remainder of FGF23-mediated hypophosphatemic disorders continue to be treated with phosphate and calcitriol, although ongoing trials with burosumab for treatment of tumor-induced osteomalacia show early promise. Burosumab may be an effective treatment for the remainder of FGF23-mediated disorders, but clinical trials to support that possibility are at present not available.
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Affiliation(s)
- Diana Athonvarangkul
- Department of Medicine Section of Endocrinology, Yale School of Medicine, PO Box 802080, New Haven, CT, 06520, USA.
| | - Karl L Insogna
- Department of Medicine Section of Endocrinology, Yale School of Medicine, PO Box 802080, New Haven, CT, 06520, USA
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175
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Deeb A, Juraibah FA, Dubayee MA, Habeb A. X-linked Hypophosphatemic Rickets: Awareness, Knowledge, and Practice of Pediatric Endocrinologists in Arab Countries. J Pediatr Genet 2020; 11:126-131. [DOI: 10.1055/s-0040-1721400] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2020] [Accepted: 10/25/2020] [Indexed: 10/22/2022]
Abstract
AbstractX-linked hypophosphatemic rickets (XLHR) is a genetic disease caused by inactivating pathogenic variants in PHEX, which results in reduced mineralization of bone, teeth, and renal phosphate wasting. XLHR is traditionally treated by phosphate and vitamin D analogs. Recently, burosumab, a recombinant anti-fibroblast growth factor-23 (FGF-23) monoclonal antibody was approved as specific XLHR therapy. We aimed to assess the awareness, knowledge, and management of XLHR among members of the Arab Society for Pediatric Endocrinology and Diabetes (ASPED). Of the 97 physicians who answered the online questionnaire, 97% were aware of XLHR, and while 90% screen family members of the index case, only 29% manage children with XLHR. In children with rickets, 40% of participants measure serum/urine phosphate routinely, and 31% request serum FGF-23 in suspected XLHR cases. Almost all responders use conventional XLHR therapy, and 4% used Burosomab. Only 14% were satisfied with the conventional treatment, and 69% reported therapeutic complications in up to 25% of their patients. Multidisciplinary care for XLHR is practiced by 94%, but 82% of providers did not have transition clinics. Pediatric endocrinologists in ASPED countries are aware of XLHR but have variable practice and are unsatisfied with its conventional treatment. Raising awareness of the recognition and modern management of XLHR is needed.
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Affiliation(s)
- Asma Deeb
- Department of Pediatric Endocrinology, Sheikh Shakhbout Medical City, Abu Dhabi, United Arab Emirates
| | - Fahad Al Juraibah
- Department of Pediatrics, Ministry of National Guard Health Affairs, Riyadh, Saudi Arabia
- Department of Pediatrics, College of Medicine, King Saud bin Abdulaziz University for Health Science, Riyadh, Saudi Arabia
| | - Muhammad Al Dubayee
- Department of Pediatrics, Ministry of National Guard Health Affairs, Riyadh, Saudi Arabia
- Department of Pediatrics, College of Medicine, King Saud bin Abdulaziz University for Health Science, Riyadh, Saudi Arabia
| | - Abdelhadi Habeb
- Department of Pediatrics, Ministry of National Guard Health Affairs, Madinah, Saudi Arabia
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176
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Abstract
FGF23 is a phosphotropic hormone produced by the bone. FGF23 works by binding to the FGF receptor-Klotho complex. Klotho is expressed in several limited tissues including the kidney and parathyroid glands. This tissue-restricted expression of Klotho is believed to determine the target organs of FGF23. FGF23 reduces serum phosphate by suppressing the expression of type 2a and 2c sodium-phosphate cotransporters in renal proximal tubules. FGF23 also decreases 1,25-dihydroxyvitamin D levels by regulating the expression of vitamin D-metabolizing enzymes, which results in reduced intestinal phosphate absorption. Excessive actions of FGF23 cause several types of hypophosphatemic rickets/osteomalacia characterized by impaired mineralization of bone matrix. In contrast, deficient actions of FGF23 result in hyperphosphatemic tumoral calcinosis with high 1,25-dihydroxyvitamin D levels. These results indicate that FGF23 is a physiological regulator of phosphate and vitamin D metabolism and indispensable for the maintenance of serum phosphate levels.
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177
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Dahir K, Roberts MS, Krolczyk S, Simmons JH. X-Linked Hypophosphatemia: A New Era in Management. J Endocr Soc 2020; 4:bvaa151. [PMID: 33204932 PMCID: PMC7649833 DOI: 10.1210/jendso/bvaa151] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 10/07/2020] [Indexed: 01/29/2023] Open
Abstract
X-linked hypophosphatemia (XLH) is a rare, hereditary, progressive musculoskeletal disease that often causes pain and short stature, as well as decreased physical function, mobility, and quality of life. Hypophosphatemia in XLH is caused by loss of function mutations in the phosphate-regulating endopeptidase homolog X-linked (PHEX) gene, resulting in excess levels of the phosphate-regulating hormone fibroblast growth factor 23 (FGF23), which leads to renal phosphate wasting and decreased serum 1,25-dihydroxyvitamin D production. Historically, treatment options were limited to oral phosphate and active vitamin D analogues (conventional management) dosed several times daily in an attempt to improve skeletal mineralization by increasing serum phosphorus. The recent approval of burosumab, a fully human monoclonal antibody to FGF23, has provided a new, targeted treatment option for patients with XLH. This review summarizes our current understanding of XLH, the safety and efficacy of conventional management and burosumab, existing recommendations for managing patients, and unanswered questions in the field.
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Affiliation(s)
- Kathryn Dahir
- Endocrinology and Diabetes, Vanderbilt University Medical Center, Nashville, Tennessee
| | | | | | - Jill H Simmons
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee
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178
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Robinson ME, AlQuorain H, Murshed M, Rauch F. Mineralized tissues in hypophosphatemic rickets. Pediatr Nephrol 2020; 35:1843-1854. [PMID: 31392510 DOI: 10.1007/s00467-019-04290-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Revised: 06/03/2019] [Accepted: 06/06/2019] [Indexed: 12/19/2022]
Abstract
Hypophosphatemic rickets is caused by renal phosphate wasting that is most commonly due to X-linked dominant mutations in PHEX. PHEX mutations cause hypophosphatemia indirectly, through the increased expression of fibroblast growth factor 23 (FGF23) by osteocytes. FGF23 decreases renal phosphate reabsorption and thereby increases phosphate excretion. The lack of phosphate leads to a mineralization defect at the level of growth plates (rickets), bone tissue (osteomalacia), and teeth, where the defect facilitates the formation of abscesses. The bone tissue immediately adjacent to osteocytes often remains unmineralized ("periosteocytic lesions"), highlighting the osteocyte defect in this disorder. Common clinical features of XLH include deformities of the lower extremities, short stature, enthesopathies, dental abscesses, as well as skull abnormalities such as craniosynostosis and Chiari I malformation. For the past four decades, XLH has been treated by oral phosphate supplementation and calcitriol, which improves rickets and osteomalacia and the dental manifestations, but often does not resolve all aspects of the mineralization defects. A newer treatment approach using inactivating FGF23 antibodies leads to more stable control of serum inorganic phosphorus levels and seems to heal rickets more reliably. However, the long-term benefits of FGF23 antibody treatment remain to be elucidated.
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Affiliation(s)
- Marie-Eve Robinson
- Shriners Hospital for Children and McGill University, 1003 Boulevard Decarie, Montreal, Québec, H4A 0A9, Canada
| | - Haitham AlQuorain
- Shriners Hospital for Children and McGill University, 1003 Boulevard Decarie, Montreal, Québec, H4A 0A9, Canada
| | - Monzur Murshed
- Shriners Hospital for Children and McGill University, 1003 Boulevard Decarie, Montreal, Québec, H4A 0A9, Canada
| | - Frank Rauch
- Shriners Hospital for Children and McGill University, 1003 Boulevard Decarie, Montreal, Québec, H4A 0A9, Canada.
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179
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Mao M, Carpenter TO, Whyte MP, Skrinar A, Chen CY, San Martin J, Rogol AD. Growth Curves for Children with X-linked Hypophosphatemia. J Clin Endocrinol Metab 2020; 105:dgaa495. [PMID: 32721016 PMCID: PMC7448934 DOI: 10.1210/clinem/dgaa495] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Accepted: 07/24/2020] [Indexed: 11/27/2022]
Abstract
CONTEXT We characterized linear growth in infants and children with X-linked hypophosphatemia (XLH). OBJECTIVE Provide linear growth curves for children with XLH from birth to early adolescence. DESIGN Data from 4 prior studies of XLH were pooled to construct growth curves. UX023-CL002 was an observational, retrospective chart review. Pretreatment data were collected from 3 interventional trials: two phase 2 trials (UX023-CL201, UX023-CL205) and a phase 3 trial (UX023-CL301). SETTING Medical centers with expertise in treating XLH. PATIENTS Children with XLH, 1-14 years of age. INTERVENTION None. MAIN OUTCOME MEASURE Height-for-age linear growth curves, including values for the 5th, 10th, 25th, 50th, 75th, 90th, and 95th percentiles for children with XLH compared to population norms. RESULTS A total of 228 patients (132 girls, 96 boys) with 2381 height measurements were included. Nearly all subjects (> 99%) reported prior management with supplementation therapy. Compared to the Center for Disease Control and Prevention growth curves, boys at age 3 months, 6 months, 9 months, 1 year, and 2 years had median height percentiles of 46%, 37%, 26%, 18%, and 5%, respectively; for girls the median height percentiles were 52%, 37%, 25%, 18%, and 7%, respectively. Annual growth in children with XLH fell below that of healthy children near 1 year of age and progressively declined during early childhood, with all median height percentiles < 8% between 2 and 12 years old. CONCLUSION Children with XLH show decreased height gain by 1 year of age and remain below population norms thereafter. These data will help evaluate therapeutic interventions on linear growth for pediatric XLH.
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Affiliation(s)
- Meng Mao
- UBiometrics, Ultragenyx Pharmaceutical Inc., Novato, California
| | - Thomas O Carpenter
- Department of Pediatrics, Department of Orthopaedics and Rehabilitation, Yale University School of Medicine, New Haven, Connecticut
| | - Michael P Whyte
- Division of Bone and Mineral Diseases, Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri
- Center for Metabolic Bone Disease and Molecular Research, Shriners Hospitals for Children - St Louis, St Louis, Missouri
| | - Alison Skrinar
- Clinical Outcomes, Research and Evaluation, Ultragenyx Pharmaceutical Inc., Novato, California
| | - Chao-Yin Chen
- UBiometrics, Ultragenyx Pharmaceutical Inc., Novato, California
| | - Javier San Martin
- Clinical Development, Ultragenyx Pharmaceutical Inc., Novato, California
| | - Alan D Rogol
- Pediatrics, University of Virginia School of Medicine, Charlottesville, Virginia
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180
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Surgical Treatment for Severe Fixed Hyperkyphosis in an Adult Patient Suffering From Ankylosing Spondylitis and Hereditary Hypophosphatemia With Vertebral Osteopetrosis. Clin Spine Surg 2020; 33:307-313. [PMID: 32453164 DOI: 10.1097/bsd.0000000000001011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE Ankylosing spondylitis and hereditary hypophosphatemia with long-term high dose supplementation of phosphorous and calcitriol can both lead to severe structural abnormalities of the vertebrae. Impairment of spinal mobility and spinal deformity may ultimately necessitate surgical treatment. A severe fixed hyperkyphosis in a patient with ankylosing spondylitis is a surgically demanding condition, therefore, the indication for surgical treatment should be thoroughly considered and chosen individually. METHODS This is an uncommon case with a combination of a severe fixed hyperkyphosis with a Cobb-angle of 105 degrees between Th2 and L4 in an adult male patient suffering from ankylosing spondylitis and X-linked hypophosphatemia with surprisingly massive osteopetrosis. In this paper, the coexisting conditions of late-stage ankylosing spondylitis and long-term treated hereditary hypophosphatemia are highlighted. The surgical treatment with different techniques, complications, and results are well explained. RESULTS A normal gait and stand were achieved by a long posterior fusion with 3 pedicle subtraction osteotomies on L1, L3, and L5. The surgical correction was performed in 3 stages. Postoperative the patient was administered to a rehabilitation center for 3 months. The hyperkyphosis, the C7 plumbline, and the pelvic retroversion were corrected. CONCLUSIONS Surgical treatment of a severe fixed hyperkyphosis due to ankylosing spondylitis is technically demanding but can be successfully achieved if all surgical challenges and comorbidities are adequately addressed including intraoperative surprising findings like osteopetrotic bone in a patient with hereditary hypophosphatemia as in our case.
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181
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Padidela R, Cheung MS, Saraff V, Dharmaraj P. Clinical guidelines for burosumab in the treatment of XLH in children and adolescents: British paediatric and adolescent bone group recommendations. Endocr Connect 2020; 9:1051-1056. [PMID: 33112809 PMCID: PMC7707830 DOI: 10.1530/ec-20-0291] [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: 09/29/2020] [Accepted: 10/08/2020] [Indexed: 12/16/2022]
Abstract
X-linked hypophosphataemia (XLH) is caused by a pathogenic variant in the PHEX gene, which leads to elevated circulating FGF23. High FGF23 causes hypophosphataemia, reduced active vitamin D concentration and clinically manifests as rickets in children and osteomalacia in children and adults. Conventional therapy for XLH includes oral phosphate and active vitamin D analogues but does not specifically treat the underlying pathophysiology of elevated FGF23-induced hypophosphataemia. In addition, adherence to conventional therapy is limited by frequent daily dosing and side effects such as gastrointestinal symptoms, secondary hyperparathyroidism and nephrocalcinosis. Burosumab, a recombinant human IgG1 MAB that binds to and inhibits the activity of FGF23, is administered subcutaneously every 2 weeks. In clinical trials (phase 2 and 3) burosumab was shown to improve phosphate homeostasis that consequently resolves the skeletal/non-skeletal manifestations of XLH. Burosumab was licensed in Europe (February 2018) with the National Institute for Health and Care Excellence, UK approving use within its marketing authorisation in October 2018. In this publication, the British Paediatric and Adolescent Bone Group (BPABG) reviewed current evidence and provide expert recommendations for care pathway and management of XLH with burosumab.
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Affiliation(s)
- Raja Padidela
- Royal Manchester Children’s Hospital and Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
- Correspondence should be addressed to R Padidela:
| | | | - Vrinda Saraff
- Birmingham Women’s and Children’s Hospital, Birmingham, UK
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182
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Hoac B, Østergaard M, Wittig NK, Boukpessi T, Buss DJ, Chaussain C, Birkedal H, Murshed M, McKee MD. Genetic Ablation of Osteopontin in Osteomalacic Hyp Mice Partially Rescues the Deficient Mineralization Without Correcting Hypophosphatemia. J Bone Miner Res 2020; 35:2032-2048. [PMID: 32501585 DOI: 10.1002/jbmr.4101] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Revised: 05/24/2020] [Accepted: 06/01/2020] [Indexed: 11/09/2022]
Abstract
PHEX is predominantly expressed by bone and tooth-forming cells, and its inactivating mutations in X-linked hypophosphatemia (XLH) lead to renal phosphate wasting and severe hypomineralization of bones and teeth. Also present in XLH are hallmark hypomineralized periosteocytic lesions (POLs, halos) that persist despite stable correction of serum phosphate (Pi ) that improves bulk bone mineralization. In XLH, mineralization-inhibiting osteopontin (OPN, a substrate for PHEX) accumulates in the extracellular matrix of bone. To investigate how OPN functions in Hyp mice (a model for XLH), double-null (Hyp;Opn-/- ) mice were generated. Undecalcified histomorphometry performed on lumbar vertebrae revealed that Hyp;Opn-/- mice had significantly reduced osteoid area/bone area (OV/BV) and osteoid thickness of trabecular bone as compared to Hyp mice, despite being as hypophosphatemic as Hyp littermate controls. However, tibias examined by synchrotron radiation micro-CT showed that mineral lacunar volumes remained abnormally enlarged in these double-null mice. When Hyp;Opn-/- mice were fed a high-Pi diet, serum Pi concentration increased, and OV/BV and osteoid thickness normalized, yet mineral lacunar area remained abnormally enlarged. Enpp1 and Ankh gene expression were increased in double-null mice fed a high-Pi diet, potentially indicating a role for elevated inhibitory pyrophosphate (PPi ) in the absence of OPN. To further investigate the persistence of POLs in Hyp mice despite stable correction of serum Pi , immunohistochemistry for OPN on Hyp mice fed a high-Pi diet showed elevated OPN in the osteocyte pericellular lacunar matrix as compared to Hyp mice fed a control diet. This suggests that POLs persisting in Hyp mice despite correction of serum Pi may be attributable to the well-known upregulation of mineralization-inhibiting OPN by Pi , and its accumulation in the osteocyte pericellular matrix. This study shows that OPN contributes to osteomalacia in Hyp mice, and that genetic ablation of OPN in Hyp mice improves the mineralization phenotype independent of systemic Pi -regulating factors. © 2020 American Society for Bone and Mineral Research.
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Affiliation(s)
- Betty Hoac
- Faculty of Dentistry, McGill University, Montreal, QC, Canada
| | - Maja Østergaard
- Department of Chemistry and the Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Aarhus, Denmark
| | - Nina K Wittig
- Department of Chemistry and the Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Aarhus, Denmark
| | - Tchilalo Boukpessi
- Faculty of Dentistry, McGill University, Montreal, QC, Canada.,EA 2496, Laboratory Orofacial Pathologies, Imaging and Biotherapies, School of Dentistry Université de Paris, Paris, France.,Assistance Publique-Hôpitaux de Paris (AP-HP) Department of Odontology, Charles Foix and Bretonneau Hospitals and Reference Center for Rare Diseases of Calcium and Phosphorus Metabolism, Paris, France
| | - Daniel J Buss
- Department of Anatomy and Cell Biology, Faculty of Medicine, McGill University, Montreal, QC, Canada
| | - Catherine Chaussain
- EA 2496, Laboratory Orofacial Pathologies, Imaging and Biotherapies, School of Dentistry Université de Paris, Paris, France.,Assistance Publique-Hôpitaux de Paris (AP-HP) Department of Odontology, Charles Foix and Bretonneau Hospitals and Reference Center for Rare Diseases of Calcium and Phosphorus Metabolism, Paris, France
| | - Henrik Birkedal
- Department of Chemistry and the Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Aarhus, Denmark
| | - Monzur Murshed
- Faculty of Dentistry, McGill University, Montreal, QC, Canada.,Department of Medicine, Faculty of Medicine, McGill University, Montreal, QC, Canada.,Shriners Hospital for Children, Montreal, QC, Canada
| | - Marc D McKee
- Faculty of Dentistry, McGill University, Montreal, QC, Canada.,Department of Anatomy and Cell Biology, Faculty of Medicine, McGill University, Montreal, QC, Canada
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183
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Serna J, Bergwitz C. Importance of Dietary Phosphorus for Bone Metabolism and Healthy Aging. Nutrients 2020; 12:E3001. [PMID: 33007883 PMCID: PMC7599912 DOI: 10.3390/nu12103001] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Revised: 09/25/2020] [Accepted: 09/26/2020] [Indexed: 12/13/2022] Open
Abstract
Inorganic phosphate (Pi) plays a critical function in many tissues of the body: for example, as part of the hydroxyapatite in the skeleton and as a substrate for ATP synthesis. Pi is the main source of dietary phosphorus. Reduced bioavailability of Pi or excessive losses in the urine causes rickets and osteomalacia. While critical for health in normal amounts, dietary phosphorus is plentiful in the Western diet and is often added to foods as a preservative. This abundance of phosphorus may reduce longevity due to metabolic changes and tissue calcifications. In this review, we examine how dietary phosphorus is absorbed in the gut, current knowledge about Pi sensing, and endocrine regulation of Pi levels. Moreover, we also examine the roles of Pi in different tissues, the consequences of low and high dietary phosphorus in these tissues, and the implications for healthy aging.
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Affiliation(s)
- Juan Serna
- Yale College, Yale University, New Haven, CT 06511, USA;
| | - Clemens Bergwitz
- Section of Endocrinology and Metabolism, Department of Internal Medicine, Yale School of Medicine, New Haven, CT 06519, USA
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184
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Faraji-Bellée CA, Cauliez A, Salmon B, Fogel O, Zhukouskaya V, Benoit A, Schinke T, Roux C, Linglart A, Miceli-Richard C, Chaussain C, Briot K, Bardet C. Development of Enthesopathies and Joint Structural Damage in a Murine Model of X-Linked Hypophosphatemia. Front Cell Dev Biol 2020; 8:854. [PMID: 33072734 PMCID: PMC7536578 DOI: 10.3389/fcell.2020.00854] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Accepted: 08/10/2020] [Indexed: 12/14/2022] Open
Abstract
X-linked hypophosphatemia (XLH) is characterized by rickets and osteomalacia, caused by inactivating mutations in the Phosphate-regulating endopeptidase homolog X-linked (PHEX) gene. With aging, adult patients develop paradoxical heterotopic calcifications of tendons and ligaments at their insertion sites (enthesophytes), and joint alterations. Understanding the progression of this structural damage that severely affects patients’ quality of life will help to improve the management of XLH. Here, we characterized the occurrence of enthesophytes and joint alterations through a 12 month in vivo micro-CT follow-up in the Hyp mouse, a murine model of XLH (n = 5 mice per group). Similar to adult patients with XLH, Hyp mice developed calcaneal enthesophytes, hip joint alterations, erosions of the sacroiliac joints and periarticular calcifications. These lesions were already present at month 3 and gradually worsened over time. In sharp contrast, no abnormalities were observed in control mice at early time points. Histological analyses confirmed the presence of bone erosions, calcifications and expansion of mineralizing enthesis fibrocartilage in Hyp mice and their absence in controls and suggested that new bone formation is driven by altered mechanical strain. Interestingly, despite a strong deformation of the curvature, none of the Hyp mice displayed enthesophyte at the spine. Peripheral enthesophytes and joint alterations develop at the early stages of the disease and gradually worsen overtime. Overall, our findings highlight the relevance of this preclinical model to test new therapies aiming to prevent bone and joint complications in XLH.
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Affiliation(s)
- Carole-Anne Faraji-Bellée
- Université de Paris, Laboratory Orofacial Pathologies, Imaging and Biotherapies UR 2496, Dental School, Montrouge, France
| | - Axelle Cauliez
- Université de Paris, Laboratory Orofacial Pathologies, Imaging and Biotherapies UR 2496, Dental School, Montrouge, France
| | - Benjamin Salmon
- Université de Paris, Laboratory Orofacial Pathologies, Imaging and Biotherapies UR 2496, Dental School, Montrouge, France.,APHP, Reference Center for Rare Disorders of the Calcium and Phosphate Metabolism, Dental Medicine Department, Bretonneau Hospital, Paris, France
| | - Olivier Fogel
- Department of Rheumatology, Cochin Hospital, Université de Paris, Reference Center for Rare Disorders of the Calcium and Phosphate Metabolism, and Reference Center for Rare Genetic Bone Diseases, Cochin Hospital, Paris, France
| | - Volha Zhukouskaya
- Université de Paris, Laboratory Orofacial Pathologies, Imaging and Biotherapies UR 2496, Dental School, Montrouge, France.,APHP, Reference Center for Rare Disorders of the Calcium and Phosphate Metabolism, Filière OSCAR and Platform of Expertise for Rare Diseases Paris-Sud, Bicêtre Paris-Sud Hospital, Le Kremlin Bicêtre, France
| | - Aurélie Benoit
- Université de Paris, URB2I, UR 4462, Dental School, Montrouge, France
| | - Thorsten Schinke
- Department of Osteology and Biomechanics, University Medical Center Hamburg Eppendorf, Hamburg, Germany
| | - Christian Roux
- Department of Rheumatology, Cochin Hospital, Université de Paris, Reference Center for Rare Disorders of the Calcium and Phosphate Metabolism, and Reference Center for Rare Genetic Bone Diseases, Cochin Hospital, Paris, France
| | - Agnès Linglart
- APHP, Reference Center for Rare Disorders of the Calcium and Phosphate Metabolism, Filière OSCAR and Platform of Expertise for Rare Diseases Paris-Sud, Bicêtre Paris-Sud Hospital, Le Kremlin Bicêtre, France.,APHP, Department of Endocrinology and Diabetology for Children, Bicêtre Paris Sud Hospital, Le Kremlin-Bicêtre, France.,Paris Sud - Paris Saclay University, Faculté de Médecine, Le Kremlin - Bicêtre, France
| | - Corinne Miceli-Richard
- Department of Rheumatology, Cochin Hospital, Université de Paris, Reference Center for Rare Disorders of the Calcium and Phosphate Metabolism, and Reference Center for Rare Genetic Bone Diseases, Cochin Hospital, Paris, France
| | - Catherine Chaussain
- Université de Paris, Laboratory Orofacial Pathologies, Imaging and Biotherapies UR 2496, Dental School, Montrouge, France.,APHP, Reference Center for Rare Disorders of the Calcium and Phosphate Metabolism, Dental Medicine Department, Bretonneau Hospital, Paris, France.,APHP, Reference Center for Rare Disorders of the Calcium and Phosphate Metabolism, Filière OSCAR and Platform of Expertise for Rare Diseases Paris-Sud, Bicêtre Paris-Sud Hospital, Le Kremlin Bicêtre, France
| | - Karine Briot
- Department of Rheumatology, Cochin Hospital, Université de Paris, Reference Center for Rare Disorders of the Calcium and Phosphate Metabolism, and Reference Center for Rare Genetic Bone Diseases, Cochin Hospital, Paris, France.,APHP, Reference Center for Rare Disorders of the Calcium and Phosphate Metabolism, Filière OSCAR and Platform of Expertise for Rare Diseases Paris-Sud, Bicêtre Paris-Sud Hospital, Le Kremlin Bicêtre, France
| | - Claire Bardet
- Université de Paris, Laboratory Orofacial Pathologies, Imaging and Biotherapies UR 2496, Dental School, Montrouge, France
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185
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Abstract
PURPOSE OF REVIEW The goal of this review is to give an overview of diagnosis and up-to-date management of major pediatric metabolic bone diseases that are associated with bone fragility, including nutritional rickets, hypophosphatemic rickets, osteogenesis imperfecta, Ehlers--Danlos syndrome, Marfan's syndrome, hypophosphatasia, osteopetrosis and skeletal fluorosis. RECENT FINDINGS During the past decade, a number of advanced treatment options have been introduced and shown to be an effective treatment in many metabolic bone disorders, such as burosumab for hypophosphatemic rickets and asfotase alfa for hypophosphatasia. On the other hand, other disorders, such as nutritional rickets and skeletal fluorosis continue to be underrecognized in many regions of the world. Genetic disorders of collagen-elastin, such as osteogenesis imperfecta, Ehlers--Danlos syndrome and Marfan's syndrome are also associated with skeletal fragility, which can be misdiagnosed as caused by non-accidental trauma/child abuse. SUMMARY It is essential to provide early and accurate diagnosis and treatment for pediatric patients with metabolic bone disorders in order to maintain growth and development as well as prevent fractures and metabolic complications.
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186
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Burosumab in X-linked hypophosphatemia and perspective for chronic kidney disease. Curr Opin Nephrol Hypertens 2020; 29:531-536. [PMID: 32701599 DOI: 10.1097/mnh.0000000000000631] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE OF REVIEW Perturbations in phosphate and vitamin D homeostasis impacts skeletal health in children and adults. Study of inherited and acquired hypophosphatemic syndromes led to the discovery of fibroblast growth factor 23 (FGF23) as a potent regulator of phosphate and vitamin D metabolism, and advanced our understanding of the pathophysiology of mineral and bone disorder in chronic kidney disease (CKD-MBD). Here, we review a recently approved therapy for patients with X-linked hypophosphatemia (XLH) using a novel anti-FGF23 antibody, burosumab, and discuss the implications of such targeted therapy in CKD. RECENT FINDINGS In children and adults with XLH, burosumab treatment significantly increased renal tubular phosphate reabsorption and normalized serum phosphorus concentrations. Prolonged treatment with burosumab showed a favorable safety profile, improved healing of rickets in children, and fractures and pseudofractures in adults. FGF23 excess in CKD is independently associated with left ventricular hypertrophy and cardiovascular mortality. Research strategies to lower FGF23 in animal models of CKD are rapidly advancing and a question that remains to be answered is whether FGF23 blockade will offer a new targeted intervention for disordered mineral metabolism in CKD. SUMMARY Findings from recently concluded clinical trials in adults and children with XLH provide evidence for improved skeletal health with burosumab therapy with normalization of phosphate and vitamin D metabolism. Targeted anti-FGF23 antibody treatment of XLH has emerged as a novel therapeutic strategy to treat an inherited disorder of FGF23 excess.
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187
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Schnabel D. Biopsychosoziales Betreuungskonzept für Kinder mit X‑chromosomaler Hypophosphatämie (XLH). Bundesgesundheitsblatt Gesundheitsforschung Gesundheitsschutz 2020; 63:813-820. [DOI: 10.1007/s00103-020-03171-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
ZusammenfassungPatienten mit einer schweren, seltenen und komplexen Erkrankung benötigen das multiprofessionelle biopsychosoziale Betreuungskonzept eines Sozialpädiatrischen Zentrums für chronisch kranke Kinder und Jugendliche. Am Beispiel der Multiorganerkrankung X‑chromosomale Hypophosphatämie (XLH), der häufigsten angeborenen Rachitisform, wird das Betreuungskonzept dargestellt.Der Erkrankung liegen inaktivierende Mutationen im „Phosphate-regulating gene with Homologies to Endopeptidases on the X‑chromosome“(PHEX)-Gen zugrunde, die zu einer vermehrten Synthese und Sekretion des Fibroblastenwachstumsfaktors 23 (FGF23) führen. FGF23 hat eine wichtige Funktion in der Phosphathomöostase. Durch die hohen FGF23-Konzentrationen kommt es über den renalen Phosphatverlust zur schweren Hypophosphatämie mit der Folge erheblicher Mineralisationsstörungen des Skelettsystems und der Zähne. Stand bis vor Kurzem nur eine konventionelle medikamentöse Therapie aus Phosphat und aktivem Vitamin D zur Verfügung, so ist nun mit dem neutralisierenden FGF23-Antikörper eine gezielte Therapie der Erkrankung möglich. Das multiprofessionelle Betreuungskonzept umfasst zahlreiche ärztliche Spezialisten und ein psychosoziales Team. Ziel der Betreuung ist es, den Patienten mit ihrer schweren chronischen Erkrankung eine altersentsprechende Partizipation ohne größere Teilhabestörung zu ermöglichen. Die Fortsetzung der Betreuung im Erwachsenenalter muss durch eine implementierte Transition sichergestellt werden.
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188
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Padidela R, Nilsson O, Makitie O, Beck-Nielsen S, Ariceta G, Schnabel D, Brandi ML, Boot A, Levtchenko E, Smyth M, Jandhyala R, Mughal Z. The international X-linked hypophosphataemia (XLH) registry (NCT03193476): rationale for and description of an international, observational study. Orphanet J Rare Dis 2020; 15:172. [PMID: 32605590 PMCID: PMC7329472 DOI: 10.1186/s13023-020-01434-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2020] [Accepted: 06/04/2020] [Indexed: 01/24/2023] Open
Abstract
BACKGROUND X-linked hypophosphataemia (XLH) is a rare, hereditary, progressive and lifelong phosphate wasting disorder characterised by pathological elevations in fibroblast growth factor (FGF) 23 concentration and activity; XLH has an incidence of approximately 1 in 20-25,000 individuals. Excess FGF23 activity leads to increased phosphate excretion in the kidneys - mediated by downregulation of renal tubular phosphate transporters - and reduced phosphate absorption in the intestines - due to impaired vitamin D activation. This results in impaired bone growth and mineralisation, short and disproportionate stature, leg bowing, musculoskeletal pain, spontaneous dental abscesses, rickets, and osteomalacia. The spectrum of manifestations differs between paediatric and adult patients. Those involved in the treatment of this condition face many challenges, including a lack of robust natural history and demographic data. This multicentre, international, rare-disease patient registry (XLH Registry) was established to address the paucity of data in XLH and to help inform future clinical practice. RESULTS The XLH Registry collects standard diagnostic and monitoring practice data, including (where applicable) diagnosis and disease progression history, treatment regimens and family history; the protocol does not mandate any interventions or clinical assessments. The XLH Registry aims to recruit 1200 paediatric and adult patients with XLH over 10 years, and several data analyses and peer-reviewed publications are expected to be generated throughout this period. A post-authorisation safety study for Bburosumab, for which the registry Sponsor is the marketing authorisation holder, will be nested as a sub-study within the XLH Registry via a subsequent protocol amendment. CONCLUSION The data collected within this rare-disease patient registry will be utilised to synthesise real-world evidence to inform the management of XLH, to improve the quality of life and standard of care of patients living with this rare debilitating disease.
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Affiliation(s)
- Raja Padidela
- Royal Manchester Children's Hospital and Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| | - Ola Nilsson
- Karolinska Institutet, Stockholm, Sweden
- Örebro University, Örebro, Sweden
| | - Outi Makitie
- Children's Hospital, Pediatric Research Center, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
| | | | - Gema Ariceta
- Hospital Vall d'Hebron, Universitat Autonoma Barcelona, Barcelona, Spain
| | - Dirk Schnabel
- Center for Chronic Sick Children, Pediatric Endocrinology, Charité, University Medicine Berlin, Berlin, Germany
| | | | | | | | | | | | - Zulf Mughal
- Royal Manchester Children's Hospital and Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
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189
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Fratzl-Zelman N, Gamsjaeger S, Blouin S, Kocijan R, Plasenzotti P, Rokidi S, Nawrot-Wawrzyniak K, Roetzer K, Uyanik G, Haeusler G, Shane E, Cohen A, Klaushofer K, Paschalis EP, Roschger P, Fratzl P, Zwerina J, Zwettler E. Alterations of bone material properties in adult patients with X-linked hypophosphatemia (XLH). J Struct Biol 2020; 211:107556. [PMID: 32619592 DOI: 10.1016/j.jsb.2020.107556] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2020] [Revised: 06/18/2020] [Accepted: 06/23/2020] [Indexed: 01/08/2023]
Abstract
X-linked hypophosphatemia (XLH) caused by PHEX mutations results in elevated serum FGF23 levels, renal phosphate wasting and low 1,25-dihydroxyvitamin D. The glycophosphoprotein osteopontin, a potent inhibitor of mineralization normally degraded by PHEX, accumulates within the bone matrix. Conventional therapy consisting of supplementation with phosphate and vitamin D analogs is burdensome and the effects on bone material poorly characterized. We analyzed transiliac bone biopsies from four adult patients, two of them severely affected due to no diagnosis and no treatment until adulthood. We used light microscopy, qBEI and FTIRI to study histology, histomorphometry, bone mineralization density distribution, properties of the organic matrix and size of hypomineralized periosteocytic lesions. Non-treatment resulted in severe osteomalacia, twice the amount of mineralized trabecular volume, multiple osteon-like perforations, continuity of lamellae from mineralized to unmineralized areas and distinctive patches of woven bone. Periosteocytic lesions were larger than in treated patients. The latter had nearly normal osteoid thicknesses, although surface was still elevated. The median calcium content of the matrix was always within normal range, although the percentage of lowly mineralized bone areas was highly increased in non-treated patients, resulting in a marked heterogeneity in mineralization. Divalent collagen cross-links were evident independently of the mineral content of the matrix. Broad osteoid seams lacked measurable pyridinoline, a mature trivalent cross-link and exhibited considerable acidic lipid content, typically found in matrix vesicles. Based on our results, we propose a model that possibly integrates the relationship between the observed mineralization disturbances, FGF23 secretion and the known osteopontin accumulation in XLH.
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Affiliation(s)
- Nadja Fratzl-Zelman
- Ludwig Boltzmann Institute of Osteology at Hanusch Hospital of OEGK and AUVA Trauma Centre Meidling, 1st Medical Department Hanusch Hospital, Vienna, Austria.
| | - Sonja Gamsjaeger
- Ludwig Boltzmann Institute of Osteology at Hanusch Hospital of OEGK and AUVA Trauma Centre Meidling, 1st Medical Department Hanusch Hospital, Vienna, Austria
| | - Stéphane Blouin
- Ludwig Boltzmann Institute of Osteology at Hanusch Hospital of OEGK and AUVA Trauma Centre Meidling, 1st Medical Department Hanusch Hospital, Vienna, Austria
| | - Roland Kocijan
- Ludwig Boltzmann Institute of Osteology at Hanusch Hospital of OEGK and AUVA Trauma Centre Meidling, 1st Medical Department Hanusch Hospital, Vienna, Austria; 1st Medical Department, Hanusch Hospital, Vienna, Austria
| | | | - Stamatia Rokidi
- Ludwig Boltzmann Institute of Osteology at Hanusch Hospital of OEGK and AUVA Trauma Centre Meidling, 1st Medical Department Hanusch Hospital, Vienna, Austria
| | - Kamilla Nawrot-Wawrzyniak
- Ludwig Boltzmann Institute of Osteology at Hanusch Hospital of OEGK and AUVA Trauma Centre Meidling, 1st Medical Department Hanusch Hospital, Vienna, Austria
| | - Katharina Roetzer
- Center for Medical Genetics, Hanusch Hospital, Vienna, Austria; Medical School, Sigmund Freud Private University, Vienna, Austria
| | - Gökhan Uyanik
- Center for Medical Genetics, Hanusch Hospital, Vienna, Austria; Medical School, Sigmund Freud Private University, Vienna, Austria
| | - Gabriele Haeusler
- Department of Pediatrics and Adolescent Medicine, Medical University of Vienna, Austria
| | - Elizabeth Shane
- Division of Endocrinology, Columbia University College of Physicians and Surgeons, New York, NY, USA
| | - Adi Cohen
- Division of Endocrinology, Columbia University College of Physicians and Surgeons, New York, NY, USA
| | - Klaus Klaushofer
- Ludwig Boltzmann Institute of Osteology at Hanusch Hospital of OEGK and AUVA Trauma Centre Meidling, 1st Medical Department Hanusch Hospital, Vienna, Austria
| | - Eleftherios P Paschalis
- Ludwig Boltzmann Institute of Osteology at Hanusch Hospital of OEGK and AUVA Trauma Centre Meidling, 1st Medical Department Hanusch Hospital, Vienna, Austria
| | - Paul Roschger
- Ludwig Boltzmann Institute of Osteology at Hanusch Hospital of OEGK and AUVA Trauma Centre Meidling, 1st Medical Department Hanusch Hospital, Vienna, Austria
| | - Peter Fratzl
- Max Planck Institute of Colloids and Interfaces, Department of Biomaterials, Potsdam, Germany
| | - Jochen Zwerina
- Ludwig Boltzmann Institute of Osteology at Hanusch Hospital of OEGK and AUVA Trauma Centre Meidling, 1st Medical Department Hanusch Hospital, Vienna, Austria; 1st Medical Department, Hanusch Hospital, Vienna, Austria
| | - Elisabeth Zwettler
- Ludwig Boltzmann Institute of Osteology at Hanusch Hospital of OEGK and AUVA Trauma Centre Meidling, 1st Medical Department Hanusch Hospital, Vienna, Austria; Medical Directorate, Hanusch Hospital, Vienna, Austria
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190
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Kubota T, Fukumoto S, Cheong HI, Michigami T, Namba N, Ito N, Tokunaga S, Gibbs Y, Ozono K. Long-term outcomes for Asian patients with X-linked hypophosphataemia: rationale and design of the SUNFLOWER longitudinal, observational cohort study. BMJ Open 2020; 10:e036367. [PMID: 32601114 PMCID: PMC7328740 DOI: 10.1136/bmjopen-2019-036367] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
INTRODUCTION X-linked hypophosphataemic rickets/osteomalacia (XLH) is a chronic, debilitating genetic disease characterised by skeletal abnormalities and growth disorder. The burden of XLH begins in childhood and continues throughout life. Conventional medical therapy with phosphate, active vitamin D and surgery do not address the underlying pathophysiology of the disease. While treatment during childhood may improve bone deformity and growth retardation, a large proportion of adult patients still fail to reach normal stature. Furthermore, adult patients with XLH report comorbidities associated with unresolved childhood disease, as well as newly developed disease-related complications and significantly impaired quality of life (QOL). Despite the multiple negative aspects of XLH, Asian consensus statements for diagnosis and management are lacking. METHODS AND ANALYSIS The Study of longitUdinal observatioN For patients with X-Linked hypOphosphataemic rickets/osteomalacia in collaboration With Asian partnERs study is a longitudinal observational cohort study of patients with XLH, designed to determine the medical characteristics and burdens (physical, emotional and financial) of this progressive disease and to evaluate the impact of treatment (including the use of burosumab) on clinical outcomes. The study was initiated in April 2018, and registration will remain open until 30 April 2022. The sample size planned for analyses is 160 patients, consisting of 100 patients in Japan and 60 patients in Korea. Up to 5 years of observation are planned per patient, from enrolment through to April 2023. Prospective and retrospective data will be collected to evaluate variables, including height/growth, rickets severity score, QOL, motor function and biomarkers for phosphate metabolism and bone turnover. ETHICS AND DISSEMINATION Ethics approval was obtained from the Ethics Committee of Osaka University, the Ethics Committee of Kyowa Kirin Co and by the Ethics Committee of each participating medical institution. Two interim analyses and associated publications are planned using retrospective and enrolment data at year 1 and results at year 3. TRIAL REGISTRATION NUMBERS NCT03745521; UMIN000031605.
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Affiliation(s)
- Takuo Kubota
- Department of Pediatrics, Graduate School of Medicine, Osaka University, Suita, Japan
| | - Seiji Fukumoto
- Fujii Memorial Institute of Medical Sciences, Institute of Advanced Medical Sciences, Tokushima University, Tokushima, Japan
| | - Hae Il Cheong
- Department of Pediatric Nephrology, Seoul National University Children's Hospital, Seoul, Republic of Korea
| | - Toshimi Michigami
- Department of Bone and Mineral Research, Osaka Women's and Children's Hospital, Izumi, Japan
| | - Noriyuki Namba
- Department of Pediatrics and Perinatology, Faculty of Medicine, Tottori University, Tottori, Japan
| | - Nobuaki Ito
- Division of Nephrology and Endocrinology, The University of Tokyo Hospital, Tokyo, Japan
| | - Shin Tokunaga
- Medical Affairs Department, Kyowa Kirin Co Ltd, Tokyo, Japan
| | - Yoshimi Gibbs
- Medical Affairs Department, Kyowa Kirin Co Ltd, Tokyo, Japan
| | - Keiichi Ozono
- Department of Pediatrics, Graduate School of Medicine, Osaka University, Suita, Japan
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191
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Mickute G, Staley K, Delaney H, Gardiner O, Hunter A, Keen R, Lockhart L, Meade N, Newman M, Ralston S, Rush E, Upadhyaya S, Regan S, Watts L, Walsh J, White P, Francis RM, Javaid MK. Rare musculoskeletal diseases in adults: a research priority setting partnership with the James Lind Alliance. Orphanet J Rare Dis 2020; 15:117. [PMID: 32430048 PMCID: PMC7238497 DOI: 10.1186/s13023-020-01398-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Accepted: 05/04/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Osteogenesis imperfecta, fibrous dysplasia/McCune-Albright syndrome and X-linked hypophosphatemia are three rare musculoskeletal diseases characterised by bone deformities, frequent fractures and pain. Little high-quality research exists on appropriate treatment and long-term management of these conditions in adults. This is further worsened by limited research funding in rare diseases and a general mismatch between the existing research priorities and those of the patients. This partnership adopted the James Lind Alliance approach to identify the top 10 research priorities for rare musculoskeletal diseases in adults through joint patient, carer and healthcare professional collaboration. RESULTS The initial survey for question collection recruited 198 respondents, submitting a total of 988 questions. 77% of the respondents were patients with a rare musculoskeletal disease. Following out-of-scope question exclusion, repeating query grouping and scientific literature check for answers, 39 questions on treatment and long-term management remained. In the second public survey, 220 respondents, of whom 85% were patients with a rare musculoskeletal disease, their carers, relatives or friends, prioritised these uncertainties, which allowed selection of the top 25. In the last stage, patients, carers and healthcare professionals gathered for a priority setting workshop to reach a consensus on the final top 10 research priorities. These focus on the uncertainties surrounding appropriate treatment and holistic long-term disease management, highlighting several aspects indirect to abnormal bone metabolism, such as extra-skeletal symptoms, psychological care of both patients and their families and disease course through ageing. CONCLUSIONS This James Lind Alliance priority setting partnership is the first to investigate rare bone diseases. The priorities identified here were developed jointly by patients, carers and healthcare professionals. We encourage researchers, funding bodies and other stakeholders to use these priorities in guiding future research for those affected by rare musculoskeletal disorders.
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Affiliation(s)
- Gerda Mickute
- Somerville College, University of Oxford, Oxford, OX2 6HD, UK.
| | - Kristina Staley
- Montague House, 4 St. Mary's Street, Ross on Wye, HR9 5HT, UK
| | | | | | | | - Richard Keen
- Royal National Orthopaedic Hospital, Stanmore, HA7 4LP, UK
| | | | | | | | - Stuart Ralston
- MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, EH4 2XU, UK
| | | | | | - Sandra Regan
- NIHR Oxford Biomedical Research Centre Project Manager, Oxford, UK
| | - Laura Watts
- NIHR Musculoskeletal Biomedical Research Unit, University of Oxford, Oxford, OX3 7LD, UK
| | - Jennifer Walsh
- Metabolic Bone Centre, Sheffield Teaching Hospitals NHS Foundation Trust, S5 7AU, Sheffield, UK
| | | | - Roger M Francis
- Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK
| | - M Kassim Javaid
- The Botnar Research Centre, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford, OX3 7LD, UK
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192
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Torregrosa JV, Sánchez Del Pozo J, Luiz Yanes MI, Muñoz Torres M. Panel Discussion: Some Aspects of the Management of Patients with X-Linked Hypophosphataemic Rickets. Adv Ther 2020; 37:121-126. [PMID: 32236878 DOI: 10.1007/s12325-019-01208-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Indexed: 12/01/2022]
Abstract
X-linked hypophosphataemia (XLH) rickets is a rare disease frequently misdiagnosed and mismanaged. Despite having clinical guidelines that offers some therapeutic recommendations based on the clinical experience of experts, physicians still have questions about some important aspects of the diagnosis and treatment of XLH, such as when the disease should be suspected, who should be in charge of the diagnosis, what should be done once the disease is diagnosed, or what therapeutic options are currently available. The objective of this paper is to answer some of the more frequent questions related to the management of patients with XLH by a group of experts participating in a scientific conference on XLH held in Madrid.
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Affiliation(s)
- José-Vicente Torregrosa
- Servicio de Nefrología y Trasplante Renal, Hospital Clinic, Universidad de Barcelona, Barcelona, Spain.
| | - Jaime Sánchez Del Pozo
- Sección de Endocrinología, Nutrición y Dismorfología Pediátrica, Servicio de Pediatría, Hospital Universitario 12 de Octubre, Madrid, Spain
| | - María Isabel Luiz Yanes
- Unidad de Nefrología Pediátrica, Servicio de Pediatría, Hospital Universitario Nuestra Señora de Candelaria, Santa Cruz de Tenerife, Spain
| | - Manuel Muñoz Torres
- Departamento de Medicina, Universidad de Granada, UGC Endocrinología y Nutrición. Hospital Universitario San Cecilio, CIBERFES, Instituto de Salud Carlos III, Instituto de Investigación Biosanitaria de Granada, Granada, Spain
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193
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Abstract
Beyond its functions in locomotion, support and protection of vital organs, bone also interacts with other organs to adjust mineral balance in response to physiological requirements. Bone remodelling is a continuous process of bone resorption and formation for the purpose of maintaining healthy bone mass and growth. Any derangement in this process can cause bone disorders with important clinical consequences. The most prominent features of bone diseases in children include early bone fractures, deformities and pain, which can persist and worsen later in life if an accurate and timely diagnosis is not achieved. Biochemical and genetic testing usually help to discriminate the aetiology of the disease, which determines the subsequent management and follow-up. This review focuses on major genetic metabolic bone diseases in children, their pathophysiological mechanisms, the potential therapeutic interventions and the possible consequences in adulthood of the disease and its treatments.
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Affiliation(s)
- Carlos Gómez-Alonso
- Unidad de Gestión Clínica de Metabolismo Óseo y Mineral, Instituto Reina Sofía de Investigación, RedinRen ISCIII, Hospital Universitario Central de Asturias, Universidad de Oviedo, Oviedo, Spain.
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194
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Jandhyala R. A novel method for observing proportional group awareness and consensus of items arising from list-generating questioning. Curr Med Res Opin 2020; 36:883-893. [PMID: 32098506 DOI: 10.1080/03007995.2020.1734920] [Citation(s) in RCA: 15] [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] [Indexed: 10/24/2022]
Abstract
Background: Current healthcare professional consensus-generating methodologies work by forcing consensus, which risks corrupting original opinions and often fails to assess prior expert knowledge awareness. Experience gained with a novel method in a progressive life-long rare disease, X-linked hypophosphataemia, which addresses these risks is presented here.Methods: Four case-studies are reported, presenting a novel methodology comprised of two survey rounds. Round 1 generated a list of items from healthcare professionals in response to an open-ended research question, alongside systematic literature reviews (when appropriate). These responses were thematically coded into mutually exclusive items then used to develop a structured questionnaire (Round 2), for which each participant identified their level of agreement using Likert scales; all responses were analyzed anonymously. Item awareness, observed agreement, consensus and prompted agreement were objectively measured.Results: The free-text responses to Round 1 tested the awareness of specific items regarding establishing a European registry for X-linked Hypophosphatemia (XLH), limitations of empirical treatment for XLH (adults and paediatrics), and triggers for treatment of XLH in adults. The four cases showed different levels of item awareness, observed consensus and degrees of prompted agreement. All participants agreed or strongly agreed with statements based on the most frequent items listed in Round 1. Less frequent Round 1 items had various degrees of prompted agreement consensus; some did not reach the consensus threshold of >50% participant agreement.Conclusions: Observed proportional group awareness and consensus is quicker than the Delphi technique and its variants, providing objective assessments of expert knowledge and standardized categorization of items regarding awareness, consensus and prompting. Further, it offers tailored management of each item in terms of educational need and further investigation.
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195
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Arango Sancho P. Complications of Phosphate and Vitamin D Treatment in X-Linked Hypophosphataemia. Adv Ther 2020; 37:105-112. [PMID: 32236871 DOI: 10.1007/s12325-019-01170-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Indexed: 01/01/2023]
Abstract
Conventional treatment of X-linked hypophosphataemia (XLH) consists in the oral administration of phosphate plus calcitriol supplements. Although this therapy has reduced bone deformities and even achieved adequate patient growth, overtreatment or low adherence could lead to subsequent consequences that may compromise the efficacy of the therapy. Some of the complications associated with phosphate and vitamin D treatment are abdominal discomfort, diarrhoea, hypokalaemia, hyperparathyroidism, hypercalcaemia or hypercalciuria, nephrocalcinosis or nephrolithiasis, and ectopic calcifications. Therefore, constant multidisciplinary monitoring of patients with XLH is necessary to prevent the manifestation of these complications and to deal with them as soon as they appear. The main objective of this article is to review the main complications arising from conventional treatment of XLH and how to deal with them.
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Affiliation(s)
- Pedro Arango Sancho
- Servicio de Nefrología Pediátrica y Trasplante Renal, Hospital Sant Joan de Déu, Barcelona, Spain.
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196
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Usefulness of X-rays in the Differential Diagnosis of Hypophosphataemic Rickets. Adv Ther 2020; 37:89-94. [PMID: 32236877 DOI: 10.1007/s12325-019-01183-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Indexed: 10/24/2022]
Abstract
Rickets and osteomalacia are two related conditions linked by the lack of mineralization of bone tissue due to a disturbance of calcium and phosphate homeostasis. Some of the most characteristic features of rickets are skeletal deformities, fractures, linear and continuous periosteal reaction, and enlargement of the metaphyseal space in an irregular and frayed form. However, these radiological findings are not exclusive to these diseases, but may also originate in children who were born prematurely or in those who have suffered physical abuse or an accident. Hence, it is important to establish a differential diagnosis. All these observations can be evidenced by radiological images using a simple X-ray. The aim of this article is to show the main radiological findings that can be found in rickets and how to establish a differential diagnosis of X-linked hypophosphataemic (XLH) rickets.
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197
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de Castro LF, Ovejero D, Boyce AM. DIAGNOSIS OF ENDOCRINE DISEASE: Mosaic disorders of FGF23 excess: Fibrous dysplasia/McCune-Albright syndrome and cutaneous skeletal hypophosphatemia syndrome. Eur J Endocrinol 2020; 182:R83-R99. [PMID: 32069220 PMCID: PMC7104564 DOI: 10.1530/eje-19-0969] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Accepted: 02/17/2020] [Indexed: 12/11/2022]
Abstract
Fibrous dysplasia/McCune-Albright Syndrome (FD/MAS), arising from gain-of-function mutations in Gαs, and cutaneous skeletal hypophosphatemia syndrome (CSHS), arising from gain-of-function mutations in the Ras/MAPK pathway, are strikingly complex, mosaic diseases with overlapping phenotypes. Both disorders are defined by mosaic skin and bone involvement, and both are complicated by increased FGF23 production. These similarities have frequently led to mis-diagnoses, primarily in patients with CSHS who are often assumed to have FD/MAS. The intriguing similarities in skeletal involvement in these genetically distinct disorders have led to novel insights into FGF23 physiology, making an understanding of FD/MAS and CSHS relevant to both clinicians and researchers interested in bone and endocrine disorders. This review will give an overview of FD/MAS and CSHS, focusing on the roles of mosaicism and FGF23 in the pathogenesis and clinical presentation of these disorders.
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Affiliation(s)
- Luis F de Castro
- Skeletal Disorders and Mineral Homeostasis Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland, USA
| | - Diana Ovejero
- Skeletal Disorders and Mineral Homeostasis Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland, USA
- Musculoskeletal Research Unit, Hospital del Mar Institute of Medical Investigation (IMIM), Barcelona, Spain
- National Research Council, Institute of Clinical Physiology, Lecce, Italy
| | - Alison M Boyce
- Skeletal Disorders and Mineral Homeostasis Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland, USA
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198
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Hughes M, Macica C, Meriano C, Doyle M. Giving Credence to the Experience of X-Linked Hypophosphatemia in Adulthood: An Interprofessional Mixed-Methods Study. J Patient Cent Res Rev 2020; 7:176-188. [PMID: 32377551 DOI: 10.17294/2330-0698.1727] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Purpose X-linked hypophosphatemia (XLH) is a rare X-linked dominant metabolic bone disease, often diagnosed in childhood but causing increasing physical debilitation and pain in adulthood. Physical comorbidities of XLH in adulthood include pervasive and early-onset degenerative arthritis, mineralizing enthesophytes and osteophytes, osteomalacia and pseudofracture, dental abscesses, and hearing loss. Methods This mixed-methods analysis included physical findings, diagnostic imaging, occupational and physical therapy assessments, and semi-structured interviews by social work to understand the functional outcomes and lived experience of XLH in adulthood, through connections between qualitative data obtained by social work and occupational therapy with the quantitative findings from other disciplines. Results Three primary themes of chronic pain, fear of falling, and lack of credence given by health care providers emerged from qualitative data and could be correlated with physical findings from functional outcome assessments These concerns contrasted with resilience, adaption, and compensation demonstrated by participants. Conclusions While new treatments may ease the burden of disease for adults with XLH, further research, increased provider awareness and education, and further development of standards of care are needed to promote accurate and adequate assessment and intervention for adults with XLH.
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Affiliation(s)
- Melissa Hughes
- Frank H. Netter MD School of Medicine, Quinnipiac University, North Haven, CT
| | - Carolyn Macica
- Frank H. Netter MD School of Medicine, Quinnipiac University, North Haven, CT
| | - Catherine Meriano
- Occupational Therapy, School of Health Sciences, Quinnipiac University, North Haven, CT
| | - Maya Doyle
- Social Work, School of Health Sciences, Quinnipiac University, North Haven, CT
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199
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Mameli C, Zichichi G, Mahmood N, Elalaoui SC, Mirza A, Dharmaraj P, Burrone M, Cattaneo E, Sheth J, Gandhi A, Kochar GS, Alkuraya FS, Kabra M, Mercurio G, Zuccotti G. Natural history of non-lethal Raine syndrome during childhood. Orphanet J Rare Dis 2020; 15:93. [PMID: 32299476 PMCID: PMC7164176 DOI: 10.1186/s13023-020-01373-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Accepted: 03/31/2020] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Raine syndrome (RS) is a rare autosomal recessive disorder caused by biallelic loss-of-function mutations of FAM20C. The most common clinical features are microcephaly, exophthalmos, hypoplastic nose and severe midface hypoplasia, leading to choanal atresia. The radiological findings include generalized osteosclerosis and brain calcifications. RS is usually lethal during the neonatal period due to severe respiratory distress. However, there exists a non-lethal RS form, the phenotype of which is extremely heterogeneous. There is paucity of data about clinical course and life expectancy of these patients. RESULTS This is the first description of follow-up features of non-lethal RS patients. Moreover, we present three unpublished cases. There are five Asian and two Arab patients. All were born to consanguineous parents. The most common neonatal comorbidity was respiratory distress secondary to choanal atresia. A variable degree of neurodevelopmental delay was seen in the majority of our cases and seizures and hearing or vision involvement were also frequent. Neurological and orthopedic issues were the most frequent complications seen at follow-up in our group. Persistent hypophosphatemic rickets was the most striking endocrinological manifestation, which was scarcely responsive to therapy with phosphate salts and alfacalcidol. Life expectancy of our patients goes beyond childhood, with the oldest of those described being 18 years old at present. CONCLUSIONS Manifestations of RS in those surviving the neonatal period are being increasingly recognized. Our study supports previous findings and provides clinical and biochemical observations and data from longer follow up. Finally, we propose multidisciplinary follow up for patients with non-lethal RS.
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Affiliation(s)
- Chiara Mameli
- Department of Pediatrics, Vittore Buzzi Children's Hospital, Department of Biomedical and Clinical Science L. Sacco, Università degli Studi di Milano, Milan, Italy.
| | - Giulia Zichichi
- Department of Pediatrics, Vittore Buzzi Children's Hospital, Università degli Studi di Milano, Milan, Italy
| | - Nasim Mahmood
- Department of General Paediatrics, Alder Hey Children's Hospital, Liverpool, UK
| | - Siham Chafai Elalaoui
- Centre de Recherche en Génomique des Pathologies Humaines (GENOPATH), Faculté de Médecine et de Pharmacie, Mohammed V University of Rabat, 10100, Rabat, Morocco
| | - Adnan Mirza
- Faculty of Paediatrics, Aga Khan University Hospital, Karachi, Pakistan
| | - Poonam Dharmaraj
- Department of Paediatric Endocrinology, Alder Hey Children's Hospital, Liverpool, UK
| | - Marco Burrone
- Department of Pediatrics, Vittore Buzzi Children's Hospital, Università degli Studi di Milano, Milan, Italy
| | - Elisa Cattaneo
- Clinical Genetics Service, V. Buzzi Children's Hospital, Università degli Studi di Milano, Milan, Italy
| | - Jayesh Sheth
- FRIGE-Institute of Human Genetics, Dept of Biochemical and Molecular Genetics, Ahmadabad, Gujarat, and Unique Hospital, Solapur, India
| | - Ajit Gandhi
- FRIGE-Institute of Human Genetics, Dept of Biochemical and Molecular Genetics, Ahmadabad, Gujarat, and Unique Hospital, Solapur, India
| | | | - Fowzan Sami Alkuraya
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - Madhulika Kabra
- Division of Genetics, Department of Paediatrics, AIIMS, New Delhi, India
| | - Giuseppe Mercurio
- Department of Pediatrics, Vittore Buzzi Children's Hospital, Università degli Studi di Milano, Milan, Italy
| | - Gianvincenzo Zuccotti
- Department of Pediatrics, Vittore Buzzi Children's Hospital, Department of Biomedical and Clinical Science L. Sacco, Università degli Studi di Milano, Milan, Italy
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200
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Boyce AM, Collins MT. Fibrous Dysplasia/McCune-Albright Syndrome: A Rare, Mosaic Disease of Gα s Activation. Endocr Rev 2020; 41:5610851. [PMID: 31673695 PMCID: PMC7127130 DOI: 10.1210/endrev/bnz011] [Citation(s) in RCA: 73] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Accepted: 10/29/2019] [Indexed: 12/14/2022]
Abstract
Fibrous dysplasia/McCune-Albright syndrome (FD/MAS) is a rare disorder of striking complexity. It arises from somatic, gain-of-function mutations in GNAS, leading to mosaic Gα s activation and inappropriate production of intracellular cyclic adenosine monophosphate (cAMP). The clinical phenotype is largely determined by the location and extent of affected tissues, and the pathophysiological effects of Gα s activation within these tissues. In bone, Gα s activation results in impaired differentiation of skeletal stem cells, leading to discrete skeletal lesions prone to fracture, deformity, and pain. Extraskeletal manifestations include a variable combination of hyperpigmented macules and hyperfunctioning endocrinopathies. Distinctive age-related changes in disease development has key effects on histologic, radiographic, and clinical features. FD/MAS thus presents along a uniquely broad clinical spectrum, and the resulting challenges in diagnosis and management can be difficult for clinicians. This review presents FD/MAS in the context of a mosaic disorder of Gα s activation, providing an intellectual framework within which to understand, evaluate, and treat this interesting disease. It includes a comprehensive summary of current understanding of FD/MAS pathogenesis, and a detailed discussion of clinical presentation and management. Critical areas of unmet need are highlighted, including discussion of key challenges and potential solutions to advance research and clinical care in FD/MAS.
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Affiliation(s)
- Alison M Boyce
- Skeletal Disorders and Mineral Homeostasis Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland
| | - Michael T Collins
- Skeletal Disorders and Mineral Homeostasis Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland
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