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Rush ET, Johnson B, Aradhya S, Beltran D, Bristow SL, Eisenbeis S, Guerra NE, Krolczyk S, Miller N, Morales A, Ramesan P, Sarafrazi S, Truty R, Dahir K. Molecular Diagnoses of X-Linked and Other Genetic Hypophosphatemias: Results From a Sponsored Genetic Testing Program. J Bone Miner Res 2022; 37:202-214. [PMID: 34633109 PMCID: PMC9298723 DOI: 10.1002/jbmr.4454] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/05/2021] [Revised: 09/27/2021] [Accepted: 10/02/2021] [Indexed: 12/20/2022]
Abstract
X-linked hypophosphatemia (XLH), a dominant disorder caused by pathogenic variants in the PHEX gene, affects both sexes of all ages and results in elevated serum fibroblast growth factor 23 (FGF23) and below-normal serum phosphate. In XLH, rickets, osteomalacia, short stature, and lower limb deformity may be present with muscle pain and/or weakness/fatigue, bone pain, joint pain/stiffness, hearing difficulty, enthesopathy, osteoarthritis, and dental abscesses. Invitae and Ultragenyx collaborated to provide a no-charge sponsored testing program using a 13-gene next-generation sequencing panel to confirm clinical XLH or aid diagnosis of suspected XLH/other genetic hypophosphatemia. Individuals aged ≥6 months with clinical XLH or suspected genetic hypophosphatemia were eligible. Of 831 unrelated individuals tested between February 2019 and June 2020 in this cross-sectional study, 519 (62.5%) individuals had a pathogenic or likely pathogenic variant in PHEX (PHEX-positive). Among the 312 PHEX-negative individuals, 38 received molecular diagnoses in other genes, including ALPL, CYP27B1, ENPP1, and FGF23; the remaining 274 did not have a molecular diagnosis. Among 319 patients with a provider-reported clinical diagnosis of XLH, 88.7% (n = 283) had a reportable PHEX variant; 81.5% (n = 260) were PHEX-positive. The most common variant among PHEX-positive individuals was an allele with both the gain of exons 13-15 and c.*231A>G (3'UTR variant) (n = 66/519). Importantly, over 80% of copy number variants would have been missed by traditional microarray analysis. A positive molecular diagnosis in 41 probands (4.9%; 29 PHEX positive, 12 non-PHEX positive) resulted in at least one family member receiving family testing. Additional clinical or family member information resulted in variant(s) of uncertain significance (VUS) reclassification to pathogenic/likely pathogenic (P/LP) in 48 individuals, highlighting the importance of segregation and clinical data. In one of the largest XLH genetic studies to date, 65 novel PHEX variants were identified and a high XLH diagnostic yield demonstrated broad insight into the genetic basis of XLH. © 2021 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).
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Affiliation(s)
- Eric T Rush
- Children's Mercy Kansas City, Kansas City, MO, USA.,Department of Pediatrics, University of Missouri - Kansas City School of Medicine, Kansas City, MO, USA.,Department of Internal Medicine, University of Kansas Medical Center, Kansas City, KS, USA
| | | | | | | | | | | | - Norma E Guerra
- Department of Pediatric Nephrology, Hospital General del Centro Médico Nacional «La Raza», Instituto Mexicano del Seguro Social (IMSS), Ciudad de México, Mexico
| | | | | | | | | | | | | | - Kathryn Dahir
- Program for Metabolic Bone Disorders, Vanderbilt University Medical Center (VUMC), Nashville, TN, USA
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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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Rothenbuhler A, Schnabel D, Högler W, Linglart A. Diagnosis, treatment-monitoring and follow-up of children and adolescents with X-linked hypophosphatemia (XLH). Metabolism 2020; 103S:153892. [PMID: 30928313 DOI: 10.1016/j.metabol.2019.03.009] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Revised: 03/22/2019] [Accepted: 03/25/2019] [Indexed: 11/19/2022]
Abstract
Early diagnosis, optimal therapeutic management and regular follow up of children with X-linked hypophosphatemia (XLH) determine their long term outcomes and future quality of life. Biochemical screening of potentially affected newborns in familial cases and improving physician's knowledge on clinical signs, symptoms and biochemical characteristics of XLH for de novo cases should lead to earlier diagnosis and treatment initiation. The follow-up of children with XLH includes clinical, biochemical and radiological monitoring of treatment (efficacy and complications) and screening for XLH-related dental, neurosurgical, rheumatological, cardiovascular, renal and ENT complications. In 2018, the European Union approved the use of burosumab, a humanized monoclonal anti-FGF23 antibody, as an alternative therapy to conventional therapy (active vitamin D analogues and phosphate supplements) in growing children with XLH and insufficiently controlled disease. Diagnostic criteria of XLH and the principles of disease management with conventional treatment or with burosumab are reviewed in this paper.
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Affiliation(s)
- Anya Rothenbuhler
- APHP, Endocrinology and Diabetology for Children, Bicêtre Paris Sud Hospital, Le Kremlin-Bicêtre, France; APHP, Reference Center for Rare Disorders of Calcium and Phosphate Metabolism, filière OSCAR, Paris, France; APHP, Platform of Expertise for Rare Disorders Paris-Sud, Bicêtre Paris Sud Hospital, Le Kremlin-Bicêtre, France.
| | - Dirk Schnabel
- Center for Chronic Sick Children, Pediatric Endocrinology, Charité, University Medicine Berlin, Germany
| | - Wolfgang Högler
- Institute of Metabolism and Systems Research, University of Birmingham, Birmingham, United Kingdom; Department of Pediatrics and Adolescent Medicine, Johannes Kepler University Linz, Linz, Austria
| | - Agnès Linglart
- APHP, Endocrinology and Diabetology for Children, Bicêtre Paris Sud Hospital, Le Kremlin-Bicêtre, France; APHP, Reference Center for Rare Disorders of Calcium and Phosphate Metabolism, filière OSCAR, Paris, France; APHP, Platform of Expertise for Rare Disorders Paris-Sud, Bicêtre Paris Sud Hospital, Le Kremlin-Bicêtre, France
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Asadzadeh Manjili F, Bakhshi Aliabad MH, Kalantar SM, Sahebzamani A, Safa A. Molecular and Biochemical Aspects of Hypophosphatemic Rickets; an Updated Review. INTERNATIONAL JOURNAL OF BASIC SCIENCE IN MEDICINE 2017. [DOI: 10.15171/ijbsm.2017.22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
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