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Vaisbich MH, de Cillo ACP, Silva BCC, DÁlva CB, de Carvalho ÉH, de Almeida JMCM, Marques LLM, Ribeiro M, da Silva MBM, de Medeiros PFV, Mendes PH. Real-world data of Brazilian adults with X-linked hypophosphatemia (XLH) treated with burosumab and comparison with other worldwide cohorts. Mol Genet Genomic Med 2024; 12:e2387. [PMID: 38337160 PMCID: PMC10858313 DOI: 10.1002/mgg3.2387] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Revised: 12/23/2023] [Accepted: 01/17/2024] [Indexed: 02/12/2024] Open
Abstract
BACKGROUND Disease-related variants in PHEX cause XLH by an increase of fibroblast growth factor 23 (FGF23) circulating levels, resulting in hypophosphatemia and 1,25(OH)2 vitamin D deficiency. XLH manifests in early life with rickets and persists in adulthood with osseous and extraosseous manifestations. Conventional therapy (oral phosphate and calcitriol) improves some symptoms, but evidence show that it is not completely effective, and it can lead to nephrocalcinosis (NC) and hyperparathyroidism (HPT). Burosumab (anti-FGF23 antibody) has shown to be effective and safety in the clinical trials. METHODS The current real-world collaborative study evaluated genetic, clinical and laboratory data of XLH Brazilian adult patients treated with burosumab. RESULTS Nineteen unrelated patients were studied. Patients reported pain, limb deformities and claudication, before burosumab initiation. 78% of them were previously treated with conventional therapy. The severity of the disease was moderate to severe (15 patients with score >5). At the baseline, 3 patients presented NC (16.7%) and 12 HPT (63%). After 16 ± 8.4 months under burosumab, we observed a significant: increase in stature (p = 0.02), in serum phosphate from 1.90 ± 0.43 to 2.67 ± 0.52 mg/dL (p = 0.02); in TmP/GFR from 1.30 ± 0.46 to 2.27 ± 0.64 mg/dL (p = 0.0001), in 1,25 (OH)2 D from 50.5 ± 23.3 to 71.1 ± 19.1 pg/mL (p = 0.03), and a decrease in iPTH from 86.8 ± 37.4 pg/mL to 66.5 ± 31.1 (p = 0.002). Nineteen variants were found (10 novel). HPT tended to develop in patients with truncated PHEX variants (p = 0.06). CONCLUSIONS This study confirms the efficacy and safety of burosumab on XLH adult patients observed in clinical trials. Additionally, we observed a decrease in iPTH levels in patients with moderate to severe HPT at the baseline.
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Affiliation(s)
| | | | - Bárbara Campolina C. Silva
- Hospital Felício Rocho, Osteometabolism Unit of Santa Casa de Belo HorizonteProfessor of Medicine at University Center of Belo Horizonte – UNIBHBelo HorizonteBrazil
| | | | - Érico Higino de Carvalho
- Instituto de Medicina Integrada Professor Fernado Figueira, recifeFederal University of PernambucoRecifeBrazil
| | | | | | - Marcia Ribeiro
- Genetic Unit of Federal University of Rio de JaneiroRio de JaneiroBrazil
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Sharova M, Markova T, Sumina M, Petukhova M, Bulakh M, Ryzhkova O, Nagornova T, Ionova S, Marakhonov A, Dadali E, Kutsev S. Rare IFT140-Associated Phenotype of Cranioectodermal Dysplasia and Features of Diagnostic Journey in Patients with Suspected Ciliopathies. Genes (Basel) 2023; 14:1553. [PMID: 37628605 PMCID: PMC10454909 DOI: 10.3390/genes14081553] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Revised: 07/21/2023] [Accepted: 07/26/2023] [Indexed: 08/27/2023] Open
Abstract
Here we present a patient with a cranioectodermal phenotype associated with pathogenic variants in the IFT140 gene. Most frequently, pathogenic variants in IFT140 correspond to the phenotype of Mainzer-Saldino syndrome. Only four patients have previously been described with this cranioectodermal phenotype and variants in IFT140. In comparison to other IFT140-cranioectodermal patients, our proband had similar skeletal features among with early onset end-stage renal failure that required kidney transplantation but did not have common ophthalmological features such as retinopathy, optic nerve atrophy, or nystagmus. Following exome sequencing, a splicing variant and exons 27-30 tandem duplication were suspected and further validated. The two other patients with Mainzer-Saldino syndrome that we described displayed a typical clinical picture but a special diagnostic journey. In both cases, at first only one pathogenic variant was detected following panel or exome NGS sequencing. Further WGS was performed for one of them where tandem duplication was found. Screening the third patient for the same tandem duplication was successful and revealed the presence of this duplication. Thus, we suggest that the description of the clinical feature polymorphism in a rare IFT140-cranioectodermal phenotype is extremely important for providing genetic counseling for families, as well as the formation of the correct diagnostic path for patients with a variant in IFT140.
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Affiliation(s)
| | | | - Maria Sumina
- State Healthcare Institution of Sverdlovsk Region “Clinical and Diagnostic Center “Mother’s and Child Health Protection”, 620067 Ekaterinburg, Russia
| | | | - Maria Bulakh
- Research Centre for Medical Genetics, 115522 Moscow, Russia
| | - Oxana Ryzhkova
- Research Centre for Medical Genetics, 115522 Moscow, Russia
| | | | - Sofya Ionova
- Research Centre for Medical Genetics, 115522 Moscow, Russia
| | | | - Elena Dadali
- Research Centre for Medical Genetics, 115522 Moscow, Russia
| | - Sergey Kutsev
- Research Centre for Medical Genetics, 115522 Moscow, Russia
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Ikegawa K, Hasegawa Y. Presentation and Diagnosis of Pediatric X-Linked Hypophosphatemia. Endocrines 2023; 4:128-137. [DOI: 10.3390/endocrines4010012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/24/2023] Open
Abstract
X-linked hypophosphatemia (XLH) is a rare type of hereditary hypophosphatemic rickets. Patients with XLH have various symptoms that lower their QOL as defined by HAQ, RAPID3, SF36-PCS, and SF36-MCS in adult patients and SF-10 and PDCOI in pediatric patients. Early diagnosis and treatment are needed to reduce the burden, but the condition is often diagnosed late in childhood. The present review aims to summarize the symptoms, radiological and biological characteristics, and long-term prognosis of pediatric XLH. Typical symptoms of XLH are lower leg deformities (age six months or later), growth impairment (first year of life or later), and delayed gross motor development with progressive lower limb deformities (second year of life or later). Other symptoms include dental abscess, bone pain, hearing impairment, and Chiari type 1 malformation. Critical, radiological findings of rickets are metaphyseal widening, cupping, and fraying, which tend to occur in the load-bearing bones. The Rickets Severity Score, validated for XLH, is useful for assessing the severity of rickets. The biochemical features of XLH include elevated FGF23, hypophosphatemia, low 1,25(OH)2D, and elevated urine phosphate. Renal phosphate wasting can be assessed using the tubular maximum reabsorption of phosphate per glomerular filtration rate (TmP/GFR), which yields low values in patients with XLH. XLH should be diagnosed early because the multisystem symptoms often worsen over time. The present review aims to help physicians diagnose XLH at an early stage.
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Abstract
Hypophosphatemic rickets typically presents in infancy or early childhood with skeletal deformities and growth plate abnormalities. The most common causes are genetic (such as X-linked hypophosphatemia), and these typically will result in lifelong hypophosphatemia and osteomalacia. Knowledge of phosphate metabolism, including the effects of fibroblast growth factor 23 (FGF23) (an osteocyte produced hormone that downregulates renal phosphate reabsorption and 1,25-dihydroxyvitamin-D (1,25(OH)2D) production), is critical to determining the underlying genetic or acquired causes of hypophosphatemia and to facilitate appropriate treatment. Serum phosphorus should be measured in any child or adult with musculoskeletal complaints suggesting rickets or osteomalacia. Clinical evaluation incudes thorough history, physical examination, laboratory investigations, genetic analysis (especially in the absence of a guiding family history), and imaging to establish etiology and to monitor severity and treatment course. The treatment depends on the underlying cause, but often includes active forms of vitamin D combined with phosphate salts, or anti-FGF23 antibody treatment (burosumab) for X-linked hypophosphatemia. The purpose of this article is to explore the approach to evaluating hypophosphatemic rickets and its treatment options.
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Affiliation(s)
- Sarah A Ackah
- Department of Medicine, Department of Pediatrics, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Erik A Imel
- Department of Medicine, Department of Pediatrics, Indiana University School of Medicine, Indianapolis, IN 46202, USA
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Tavana N, Ting TH, Lai K, Kennerson ML, Thilakavathy K. Whole exome sequencing identifies two novel variants in PHEX and DMP1 in Malaysian children with hypophosphatemic rickets. Ital J Pediatr 2022; 48:193. [PMID: 36482408 PMCID: PMC9730657 DOI: 10.1186/s13052-022-01385-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Accepted: 11/15/2022] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Hypophosphatemic rickets (HR) is a genetic disease of phosphate wasting that is characterized by defective bone mineralization. The most common cause of the disease is mutations in the phosphate regulating gene with homologies to endopeptidases on the X chromosome (PHEX) gene. The aims of this study were to identify the gene variants responsible for HR in three cases of Malaysian origin from three independent families and to describe their clinical, biochemical, and radiological features. METHODS Whole exome sequencing (WES) was performed on all patients and their parents, followed by Sanger sequencing validation. Bioinformatics tools were used to provide supporting evidence for pathogenicity of variants. To confirm that a mutation is de novo, paternity test was carried out. High resolution melting curve analysis was performed to assess the allele frequency in normal controls for mutations that were found in the patients. RESULTS The patients showed typical characteristics of HR including lower limb deformity, hypophosphatemia, and elevated alkaline phosphatase. WES revealed two variants in the PHEX gene and one variant in the dentin matrix protein 1 (DMP1) gene. Two of the three variants were novel, including c.1946_1954del (p.Gly649_Arg651del) in PHEX and c.54 + 1G > A in DMP1. Our data suggests that the novel p.Gly649_Arg651del variant is likely pathogenic for HR disease. CONCLUSIONS This study extends the variant spectrum of the PHEX and DMP1 genes. Our findings indicate that WES is an advantageous approach for diagnosis of genetic diseases which are heterogeneous.
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Affiliation(s)
- Nahid Tavana
- grid.11142.370000 0001 2231 800XDepartment of Biomedical Science, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, UPM Serdang, Selangor Malaysia
| | - Tzer Hwu Ting
- grid.11142.370000 0001 2231 800XDepartment of Paediatrics, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, UPM Serdang, Selangor Malaysia
| | - Kaitao Lai
- grid.1013.30000 0004 1936 834XNorthcott Neuroscience Laboratory, ANZAC Research Institute, University of Sydney, Concord, NSW Australia ,grid.1013.30000 0004 1936 834XSydney Medical School, University of Sydney, Sydney, NSW Australia
| | - Marina L. Kennerson
- grid.1013.30000 0004 1936 834XNorthcott Neuroscience Laboratory, ANZAC Research Institute, University of Sydney, Concord, NSW Australia ,grid.414685.a0000 0004 0392 3935Molecular Medicine Laboratory, Concord Hospital, Concord, NSW Australia
| | - Karuppiah Thilakavathy
- grid.11142.370000 0001 2231 800XDepartment of Biomedical Science, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, UPM Serdang, Selangor Malaysia ,grid.11142.370000 0001 2231 800XGenetics and Regenerative Medicine Research Group, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, UPM Serdang, Selangor Malaysia
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AlSubaihin A, Harrington J. Hereditary Rickets: A Quick Guide for the Pediatrician. Curr Pediatr Rev 2022; 19:CPR-EPUB-128008. [PMID: 36475338 DOI: 10.2174/1573396319666221205123402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Revised: 09/10/2022] [Accepted: 11/01/2022] [Indexed: 12/12/2022]
Abstract
With the increased discovery of genes implicated in vitamin D metabolism and the regulation of calcium and phosphate homeostasis, a growing number of genetic forms of rickets are now recognized. These are categorized into calciopenic and phosphopenic rickets. Calciopenic forms of hereditary rickets are caused by genetic mutations that alter the enzymatic activity in the vitamin D activation pathway or impair the vitamin D receptor action. Hereditary forms of phosphopenic rickets, on the other hand, are caused by genetic mutations that lead to increased expression of FGF23 hormone or that impair the absorptive capacity of phosphate at the proximal renal tubule. Due to the clinical overlap between acquired and genetic forms of rickets, identifying children with hereditary rickets can be challenging. A clear understanding of the molecular basis of hereditary forms of rickets and their associated biochemical patterns allow the health care provider to assign the correct diagnosis, avoid non-effective interventions and shorten the duration of the diagnostic journey in these children. In this mini-review, known forms of hereditary rickets listed on the Online Mendelian Inheritance in Man database are discussed. Further, a clinical approach to identify and diagnose children with hereditary forms of rickets is suggested.
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Affiliation(s)
- Abdulmajeed AlSubaihin
- Department of Pediatrics, College of Medicine, King Saud University, Riyadh, Saudi Arabia
- King Saud University Medical City, Riyadh, Saudi Arabia
| | - Jennifer Harrington
- Division of Endocrinology, Women's and Children's Health Network, North Adelaide, Australia
- Faculty of Health and Medical Sciences, University of Adelaide, Adelaide, Australia
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Alhamoudi KM, Alghamdi B, Alswailem M, Nasir A, Aljomaiah A, Al-Hindi H, Alzahrani AS. A Unique Mechanism of a Novel Synonymous PHEX Variant Causing X-Linked Hypophosphatemia. J Clin Endocrinol Metab 2022; 107:2883-2891. [PMID: 35896147 DOI: 10.1210/clinem/dgac435] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2022] [Indexed: 11/19/2022]
Abstract
CONTEXT Synonymous mutations are usually nonpathogenic. OBJECTIVE We report here a family with X-linked hypophosphatemia (XLH) due to a novel synonymous PHEX variant with a unique mechanism. METHODS We studied a 4-member family (a mother, a son, and 2 daughters), all affected with XLH. Genomic DNA was extracted from peripheral leucocytes. Whole exome sequencing (WES) was used to identify the underlying genetic variant in the proband (the son). Sanger sequencing was used to confirm this variant in the proband and his family members. RT-PCR and sequencing of the cDNA revealed the effect of this variant on the PHEX structure and function. RESULTS A synonymous variant in the PHEX gene (c.1701A>C) was identified in all affected members. This variant changes the first nucleotide of exon 17 from adenine to cytosine. Using RT-PCR, this variant was shown to interfere with splicing of exons 16 with 17 resulting in a single shorter PHEX transcript in the proband compared to normal control. Sanger sequencing of the cDNA revealed a complete skipping of exon 17 and direct splicing of exons 16 and 18. This led to a frameshift and an introduction of a new stop codon in the next codon (codon 568), which ultimately led to truncation and loss of the final 183 amino acids of PHEX. CONCLUSION This novel variant shows how a synonymous exonic mutation may induce a complex series of changes in the transcription and translation of the gene and causes a disease, a mechanism that is not commonly recognized.
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Affiliation(s)
- Kheloud M Alhamoudi
- Department of Molecular Oncology, King Faisal Specialist Hospital & Research Centre, MBC#03, PO BOX 3354, Riyadh, 11211, Saudi Arabia
| | - Balgees Alghamdi
- Department of Molecular Oncology, King Faisal Specialist Hospital & Research Centre, MBC#03, PO BOX 3354, Riyadh, 11211, Saudi Arabia
| | - Meshael Alswailem
- Department of Molecular Oncology, King Faisal Specialist Hospital & Research Centre, MBC#03, PO BOX 3354, Riyadh, 11211, Saudi Arabia
| | - Abdul Nasir
- Department of Molecular science and Technology, Ajou University, Suwon, 443-749, South Korea
| | - Abeer Aljomaiah
- Department of Medicine, King Faisal Specialist Hospital & Research Centre, P.O Box 3354, Riyadh 11211, Saudi Arabia
| | - Hindi Al-Hindi
- Department of Pathology and Laboratory Medicine, King Faisal Specialist Hospital & Research Centre, P.O Box 3354, Riyadh 11211, Saudi Arabia
| | - Ali S Alzahrani
- Department of Molecular Oncology, King Faisal Specialist Hospital & Research Centre, MBC#03, PO BOX 3354, Riyadh, 11211, Saudi Arabia
- Department of Medicine, King Faisal Specialist Hospital & Research Centre, P.O Box 3354, Riyadh 11211, Saudi Arabia
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Ohata Y, Ishihara Y. Pathogenic Variants of the PHEX Gene. Endocrines 2022; 3:498-511. [DOI: 10.3390/endocrines3030040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Twenty-five years ago, a pathogenic variant of the phosphate-regulating endopeptidase homolog X-linked (PHEX) gene was identified as the cause of X-linked hypophosphatemic rickets (XLH). Subsequently, the overproduction of fibroblast growth factor 23 (FGF23) due to PHEX defects has been found to be associated with XLH pathophysiology. However, the mechanism by which PHEX deficiency contributes to the upregulation of FGF23 and the function of PHEX itself remain unclear. To date, over 700 pathogenic variants have been identified in patients with XLH, and functional assays and genotype–phenotype correlation analyses based on pathogenic variant data derived from XLH patients have been reported. Genetic testing for XLH is useful for the diagnosis. Not only have single-nucleotide variants causing missense, nonsense, and splicing variants and small deletion/insertion variants causing frameshift/non-frameshift alterations been observed, but also gross deletion/duplication variants causing copy number variants have been reported as pathogenic variants in PHEX. With the development of new technologies including next generation sequencing, it is expected that an increasing number of pathogenic variants will be identified. This chapter aimed to summarize the genotype of PHEX and related analyses and discusses the pathophysiology of PHEX defects to seek clues on unsolved questions.
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Jurca CM, Iuhas O, Kozma K, Petchesi CD, Zaha DC, Bembea M, Jurca S, Paul C, Jurca AD. Effects of Burosumab Treatment on Two Siblings with X-Linked Hypophosphatemia. Case Report and Literature Review. Genes (Basel) 2022; 13:genes13081392. [PMID: 36011303 PMCID: PMC9407333 DOI: 10.3390/genes13081392] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Revised: 08/01/2022] [Accepted: 08/03/2022] [Indexed: 11/16/2022] Open
Abstract
X-linked hypophosphatemia (XLH) or vitamin D-resistant rickets (MIM#307800), is a monogenic disorder with X-linked inheritance. It is caused by mutations present in the Phosphate Regulating Endopeptidase Homolog X-Linked (PHEX) gene responsible for the degradation of the bone-derived hormone fibroblast growth factor 23 (FGF23) into inactive fragments, but the entire mechanism is currently unclear. The inactivation of the gene prevents the degradation of FGF23, causing increased levels of FGF23, which leads to decreased tubular reabsorbtion of phosphorus. Clinical aspects are growth delay, limb deformities, bone pain, osteomalacia, dental anomalies, and enthesopathy. Laboratory evaluation shows hypophosphatemia, elevated alkaline phosphatase (ALP), and normal serum calcium levels, whereas parathormone (PTH) may be normal or increased and FGF23 greatly increased. Conventional treatment consists of administration of oral phosphate and calcitriol. Treatment with Burosumab, a monoclonal antibody that binds to FGF23, reducing its activity, was approved in 2018. Methods. We describe a case of two siblings, a girl and a boy, diagnosed with XLH, monitored by the Genetic Department of the County Emergency Clinical Hospital since 2019. The clinical picture is suggestive for XLH, both siblings exhibiting short stature, lower limb curvature, bone pain, marked walking weakness, and fatigue. Radiological aspects showed marked deformity of the lower limbs: genu varum in the girl, genu varum and valgum in the boy. Laboratory investigations showed hypophosphathemia, hyperphosphaturia, elevated ALP, normal PTH, and highly increased FGF23 in both. DNA analysis performed on the two siblings revealed a nonsense mutation in exone 5 of the PHEX gene: NM_000444.6(PHEX):c.565C > T (p.Gln189Ter). Results. At the age of 13½ on 7 June 2021, the two children started treatment with Burosumab in therapeutic doses and were monitored clinically and biochemically at regular intervals according to the protocol established by the Endocrinology Commission of the Romanian Health Ministry. Conclusions. The first results of the Burosumab treatment in the two siblings are extremely encouraging and suggest a favorable long-term evolution under this treatment.
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Affiliation(s)
- Claudia Maria Jurca
- Faculty of Medicine and Pharmacy, Department of Preclinical Disciplines, 1 December Sq., University of Oradea, 410081 Oradea, Romania
- Regional Center of Medical Genetics Bihor, County Emergency Clinical Hospital Oradea, Romania, (Part of ERN THACA), 410469 Oradea, Romania
| | - Oana Iuhas
- Regional Center of Medical Genetics Bihor, County Emergency Clinical Hospital Oradea, Romania, (Part of ERN THACA), 410469 Oradea, Romania
| | - Kinga Kozma
- Faculty of Medicine and Pharmacy, Department of Preclinical Disciplines, 1 December Sq., University of Oradea, 410081 Oradea, Romania
- Regional Center of Medical Genetics Bihor, County Emergency Clinical Hospital Oradea, Romania, (Part of ERN THACA), 410469 Oradea, Romania
| | - Codruta Diana Petchesi
- Faculty of Medicine and Pharmacy, Department of Preclinical Disciplines, 1 December Sq., University of Oradea, 410081 Oradea, Romania
- Correspondence:
| | - Dana Carmen Zaha
- Faculty of Medicine and Pharmacy, Department of Preclinical Disciplines, 1 December Sq., University of Oradea, 410081 Oradea, Romania
| | - Marius Bembea
- Faculty of Medicine and Pharmacy, Department of Preclinical Disciplines, 1 December Sq., University of Oradea, 410081 Oradea, Romania
| | - Sanziana Jurca
- Faculty of Medicine and Pharmacy, Department of Preclinical Disciplines, 1 December Sq., University of Oradea, 410081 Oradea, Romania
| | - Corina Paul
- Department of Pediatrics, Victor Babes University of Medicine and Pharmacy, 300041 Timisoara, Romania
| | - Alexandru Daniel Jurca
- Faculty of Medicine and Pharmacy, Department of Preclinical Disciplines, 1 December Sq., University of Oradea, 410081 Oradea, Romania
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Xu T, Tao X, Zhang Z, Yue H. Clinical and genetic characteristics of 29 Chinese patients with X-linked hypophosphatemia. Front Endocrinol (Lausanne) 2022; 13:956646. [PMID: 36060934 PMCID: PMC9437435 DOI: 10.3389/fendo.2022.956646] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Accepted: 08/02/2022] [Indexed: 11/18/2022] Open
Abstract
OBJECTIVE The aim of this study was to fully describe the clinical and genetic characteristics, including clinical manifestations, intact fibroblast growth factor 23 (iFGF23) levels, and presence of PHEX gene mutations, of 22 and 7 patients with familial and sporadic X-linked dominant hypophosphatemia (XLH), respectively. METHODS Demographic data, clinical features, biochemical indicators, and imaging data of 29 patients were collected. All 22 exons and exon-intron boundaries of the PHEX gene were amplified by polymerase chain reaction (PCR) and directly sequenced. The serum level of iFGF23 was measured in 15 of the patients. RESULTS Twenty-nine patients (male/female: 13:16, juvenile/adult: 15:14) with XLH were included. The main symptoms were bowed lower extremities (89.7%), abnormal gait (89.7%), and short stature/growth retardation (78.6%). Hypophosphatemia with a high alkaline phosphatase level was the main biochemical feature and the median value of serum iFGF23 was 55.7 pg/ml (reference range: 16.1-42.2 pg/ml). Eight novel mutations in the PHEX gene were identified by Sanger sequencing, including two missense mutations (p. Gln682Leu and p. Phe312Ser), two deletions (c.350_356del and c.755_761del), one insertion (c.1985_1986insTGAC), and three splice mutations (c.1700+5G>C, c.1966-1G>T, and c.350-14_350-1del). Additionally, the recurrence rate after the first orthopedic surgery was 77.8% (7/9), and five of them had their first surgery before puberty. CONCLUSION Our study expanded the clinical phenotypes and gene mutation spectrum of XLH and provided a reference for the optimal timing of orthopedic surgeries.
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Affiliation(s)
| | | | | | - Hua Yue
- *Correspondence: Hua Yue, ; Zhenlin Zhang,
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Brener R, Zeitlin L, Lebenthal Y, Brener A. Dental health of pediatric patients with X-linked hypophosphatemia (XLH) after three years of burosumab therapy. Front Endocrinol (Lausanne) 2022; 13:947814. [PMID: 36051396 PMCID: PMC9425915 DOI: 10.3389/fendo.2022.947814] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Accepted: 07/18/2022] [Indexed: 11/13/2022] Open
Abstract
An inactivating PHEX gene mutation with the resultant accumulation of several mineralization-inhibiting proteins (e.g., FGF23) causes skeletal and dental morbidity in X-linked hypophosphatemia (XLH). This prospective case-control study explored the effect of burosumab, an anti-FGF23 antibody, on dental health of children with XLH. Ten children (age 4.3-15 years) with XLH underwent burosumab treatment per protocol. Assessment of their dental status at treatment initiation and after 1 and 3 years of treatment included clinical, laboratory and radiographic evaluation of rickets and dentition. Orthopantomographic examinations of ten healthy sex- and age-matched controls were selected for comparison. Coronal and pulp dimensions of a selected permanent mandibular molar were measured with Planmeca Romexis® software. One year of treatment led to improvement of height z-score (p=0.019) and healing of the rickets (p<0.001) in the XLH patients, and those achievements were maintained after three years of treatment. Dental morphology of XLH patients, distinguished by increased pulp-coronal ratios compared to controls (p=0.002), remained larger after the first year of treatment (p<0.001) and did not attain the decrease expected with age after three years of treatment. Five patients had a history of recurrent dental abscesses, with three having undergone at least one episode during the year before burosumab initiation. One patient sustained recurrent abscesses throughout three years of treatment. The persistence of the unique dental morphology of XLH patients undergoing burosumab therapy, as evidenced by excessively larger pulp dimensions, supports the role of other PHEX gene-related local mineralization inhibitors, such as osteopontin, in the pathogenesis of dental morbidity.
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Affiliation(s)
- Rafi Brener
- The Endodontic Unit, Galilee College of Dental Sciences, Galilee Medical Center, Nahariya, Israel
- Azrieli Faculty of Medicine, Bar-Ilan University, Safed, Israel
| | - Leonid Zeitlin
- The Metabolic Bone Disease Unit, Dana-Dwek Children’s Hospital, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel
- Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Yael Lebenthal
- Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
- The Pediatric Endocrinology and Diabetes Unit, Dana-Dwek Children’s Hospital, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel
| | - Avivit Brener
- Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
- The Pediatric Endocrinology and Diabetes Unit, Dana-Dwek Children’s Hospital, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel
- *Correspondence: Avivit Brener,
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Ishihara Y, Ohata Y, Takeyari S, Kitaoka T, Fujiwara M, Nakano Y, Yamamoto K, Yamada C, Yamamoto K, Michigami T, Mabe H, Yamaguchi T, Matsui K, Tamada I, Namba N, Yamamoto A, Etoh J, Kawaguchi A, Kosugi R, Ozono K, Kubota T. Genotype-phenotype analysis, and assessment of the importance of the zinc-binding site in PHEX in Japanese patients with X-linked hypophosphatemic rickets using 3D structure modeling. Bone 2021; 153:116135. [PMID: 34333162 DOI: 10.1016/j.bone.2021.116135] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Revised: 07/09/2021] [Accepted: 07/26/2021] [Indexed: 11/25/2022]
Abstract
X-linked hypophosphatemic rickets (XLH) is an inheritable type of rickets caused by inactivating variants in the phosphate regulating endopeptidase homolog X-linked (PHEX) gene, which results in the overproduction of fibroblast growth factor 23 (FGF23). The mechanism by which PHEX impairment leads to FGF23 overproduction is unknown. Because little is known regarding the genotype-phenotype correlation in Japanese XLH, we summarized the available clinical and genetic data and analyzed the genotype-phenotype relationships using 3-dimensional (3D) structure modeling to clarify the XLH pathophysiology. We retrospectively reviewed the clinical features and performed genetic analysis of 39 Japanese patients with XLH from 28 unrelated pedigrees carrying any known or novel PHEX variant. To predict changes in the 3D structure of mutant PHEX, we constructed a putative 3D model of each mutant and evaluated the effect of structural alteration by genotype-phenotype correlation analysis. Genetic analysis revealed 23 PHEX variants, including eight novel variants. They were associated with high i-FGF23 levels, hypophosphatemia, phosphaturia, high alkaline phosphatase levels, and short stature. No gene dosage effect or genotype-phenotype correlation was observed when truncating and non-truncating variants were compared. However, the conservation of the zinc-binding site and cavity in PHEX had an impact on the elevation of i-FGF23 levels. Via genotype-phenotype relationship analysis using 3D modeling, we showed that the zinc-binding site and cavity in PHEX can play a critical role in its function. These findings provide new genetic clues for investigating the function of PHEX and the pathogenesis of XLH.
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Affiliation(s)
- Yasuki Ishihara
- Department of Pediatrics, Osaka University Graduate School of Medicine, Suita, Japan; The 1st. Department of Oral and Maxillofacial Surgery, Osaka University Graduate School of Dentistry, Suita, Japan; Department of Cardiovascular Medicine, Osaka University Graduate School of Medicine, Suita, Japan
| | - Yasuhisa Ohata
- Department of Pediatrics, Osaka University Graduate School of Medicine, Suita, Japan
| | - Shinji Takeyari
- Department of Pediatrics, Osaka University Graduate School of Medicine, Suita, Japan
| | - Taichi Kitaoka
- Department of Pediatrics, Osaka University Graduate School of Medicine, Suita, Japan
| | - Makoto Fujiwara
- Department of Pediatrics, Osaka University Graduate School of Medicine, Suita, Japan; The 1st. Department of Oral and Maxillofacial Surgery, Osaka University Graduate School of Dentistry, Suita, Japan
| | - Yukako Nakano
- Department of Pediatrics, Osaka University Graduate School of Medicine, Suita, Japan
| | - Kenichi Yamamoto
- Department of Pediatrics, Osaka University Graduate School of Medicine, Suita, Japan; Department of Statistical Genetics, Osaka University Graduate School of Medicine, Suita, Japan
| | - Chieko Yamada
- Department of Pediatrics, Osaka University Graduate School of Medicine, Suita, Japan
| | - Katsusuke Yamamoto
- Department of Pediatric Nephrology and Metabolism, Osaka Women's and Children's Hospital, Izumi, Japan
| | - Toshimi Michigami
- Department of Bone and Mineral Research, Osaka Women's and Children's Hospital, Izumi, Japan
| | - Hiroyo Mabe
- Department of Pediatrics, Kumamoto University Hospital, Kumamoto, Japan
| | - Takeshi Yamaguchi
- Department of Pediatrics, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Katsuyuki Matsui
- Department of Pediatrics, Shiga University of Medical Science, Otsu, Japan
| | - Izumi Tamada
- Department of Pediatrics, Imakiire General Hospital, Kagoshima, Japan
| | - Noriyuki Namba
- Department of Pediatrics, Osaka University Graduate School of Medicine, Suita, Japan; Division of Pediatrics and Perinatology, Faculty of Medicine, Tottori University, Tottori, Japan
| | - Akiko Yamamoto
- Department of Pediatrics, Kumamoto Chuo Hospital, Kumamoto, Japan
| | - Junya Etoh
- Department of Pediatrics, Saga-Ken Medical Centre Koseikan, Saga, Japan
| | - Azusa Kawaguchi
- Department of Pediatrics, National Hospital Organization Hokkaido Medical Center, Sapporo, Japan
| | - Rieko Kosugi
- Department of Diabetes and Endocrinology, Shizuoka General Hospital, Shizuoka, Japan
| | - Keiichi Ozono
- Department of Pediatrics, Osaka University Graduate School of Medicine, Suita, Japan
| | - Takuo Kubota
- Department of Pediatrics, Osaka University Graduate School of Medicine, Suita, Japan.
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13
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Sarafrazi S, Daugherty SC, Miller N, Boada P, Carpenter TO, Chunn L, Dill K, Econs MJ, Eisenbeis S, Imel EA, Johnson B, Kiel MJ, Krolczyk S, Ramesan P, Truty R, Sabbagh Y. Novel PHEX gene locus-specific database: Comprehensive characterization of vast number of variants associated with X-linked hypophosphatemia (XLH). Hum Mutat 2021; 43:143-157. [PMID: 34806794 PMCID: PMC9299612 DOI: 10.1002/humu.24296] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Revised: 11/17/2021] [Accepted: 11/18/2021] [Indexed: 02/01/2023]
Abstract
X‐linked hypophosphatemia (XLH), the most common form of hereditary hypophosphatemia, is caused by disrupting variants in the PHEX gene, located on the X chromosome. XLH is inherited in an X‐linked pattern with complete penetrance observed for both males and females. Patients experience lifelong symptoms resulting from chronic hypophosphatemia, including impaired bone mineralization, skeletal deformities, growth retardation, and diminished quality of life. This chronic condition requires life‐long management with disease‐specific therapies, which can improve patient outcomes especially when initiated early in life. To centralize and disseminate PHEX variant information, we have established a new PHEX gene locus‐specific database, PHEX LSDB. As of April 30, 2021, 870 unique PHEX variants, compiled from an older database of PHEX variants, a comprehensive literature search, a sponsored genetic testing program, and XLH clinical trials, are represented in the PHEX LSDB. This resource is publicly available on an interactive, searchable website (https://www.rarediseasegenes.com/), which includes a table of variants and associated data, graphical/tabular outputs of genotype‐phenotype analyses, and an online submission form for reporting new PHEX variants. The database will be updated regularly with new variants submitted on the website, identified in the published literature, or shared from genetic testing programs.
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Affiliation(s)
- Soodabeh Sarafrazi
- Medical Affairs, Ultragenyx Pharmaceutical, Inc., Novato, California, USA
| | - Sean C Daugherty
- Medical Affairs, Ultragenyx Pharmaceutical, Inc., Novato, California, USA
| | - Nicole Miller
- Medical Affairs, Ultragenyx Pharmaceutical, Inc., Novato, California, USA
| | - Patrick Boada
- Medical Affairs, Ultragenyx Pharmaceutical, Inc., Novato, California, USA
| | - Thomas O Carpenter
- Department of Pediatrics (Endocrinology), Yale University School of Medicine, New Haven, Connecticut, USA
| | - Lauren Chunn
- Data Science, Genomenon Inc., Ann Arbor, Michigan, USA
| | - Kariena Dill
- Medical Affairs, Ultragenyx Pharmaceutical, Inc., Novato, California, USA
| | - Michael J Econs
- Division of Endocrinology and Metabolism, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Scott Eisenbeis
- Medical Affairs, Ultragenyx Pharmaceutical, Inc., Novato, California, USA
| | - Erik A Imel
- Division of Endocrinology and Metabolism, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Britt Johnson
- Medical Affairs, Invitae Corporation, San Francisco, California, USA
| | - Mark J Kiel
- Data Science, Genomenon Inc., Ann Arbor, Michigan, USA
| | - Stan Krolczyk
- Medical Affairs, Ultragenyx Pharmaceutical, Inc., Novato, California, USA
| | - Prameela Ramesan
- Medical Affairs, Ultragenyx Pharmaceutical, Inc., Novato, California, USA
| | - Rebecca Truty
- External Relations, Invitae Corporation, San Francisco, California, USA
| | - Yves Sabbagh
- Research and Development, Inozyme Pharma, Boston, Massachusetts, USA
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14
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Metwalley K, Farghaly H. Hormone resistance in children: what primary care physicians need to know. Acta Biomed 2021; 92:e2021255. [PMID: 34487068 PMCID: PMC8477115 DOI: 10.23750/abm.v92i4.11613] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Accepted: 05/28/2021] [Indexed: 01/13/2023]
Abstract
Hormone resistance is defined as a reduced or absence of target tissues responsiveness to a hormone, where the presentation is related to either a relative lack or excess of hormones. Various disorders of hormone resistance were encountered including, Laron syndrome, nephrogenic diabetes insipidus, thyroid hormone resistance syndrome, pseudohypoparathyroidism, insulin resistance, familial glucocorticoid deficiency, pseudohypoaldosteronism, X linked hypophosphatemic rickets and androgen insensitivity syndrome. The article gives a summary that presents, in concentrated form, what the primary care physicians need to know about recognition, clinical presentation, diagnosis, and management of various hormone resistance in children.
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Affiliation(s)
- Kotb Metwalley
- Department of Pediatrics, Faculty of Medicine, Assiut University, Assiut, Egypt..
| | - Hekma Farghaly
- Department of Pediatrics, Faculty of Medicine, Assiut University, Assiut, Egypt..
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15
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Lin X, Li S, Zhang Z, Yue H. Clinical and Genetic Characteristics of 153 Chinese Patients With X-Linked Hypophosphatemia. Front Cell Dev Biol 2021; 9:617738. [PMID: 34141703 PMCID: PMC8204109 DOI: 10.3389/fcell.2021.617738] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Accepted: 04/16/2021] [Indexed: 11/27/2022] Open
Abstract
X-linked hypophosphatemia (XLH) is caused by inactivating mutations in the phosphate-regulating endopeptidase homolog, X-linked (PHEX) gene, resulting in an excess of circulating intact fibroblast growth factor-23 (iFGF-23) and a waste of renal phosphate. In the present study, we retrospectively reviewed the clinical and molecular features of 153 Chinese patients, representing 87 familial and 66 sporadic cases with XLH. A total of 153 patients with XLH presented with signs or symptoms at a median age of 18.0 months (range, 9.0 months–26.0 years). Lower-limb deformity was the most frequent clinical manifestation, accounting for 79.1% (121/153). Biochemical screening showed increased serum levels of iFGF23 in patients with XLH, with a wide variation ranging from 14.39 to 730.70 pg/ml. Median values of serum iFGF23 in pediatric and adult patients were 94.87 pg/ml (interquartile range: 74.27–151.86 pg/ml) and 72.82 pg/ml (interquartile range: 39.42–136.00 pg/ml), respectively. Although no difference in circulating iFGF23 levels between these two groups was observed (P = 0.062), the proportion of patients with high levels of circulating iFGF23 (>42.2 pg/ml) was greater in the pediatric group than in the adult group (P = 0.026). Eighty-eight different mutations in 153 patients were identified, with 27 (30.7%) being novel. iFGF23 levels and severity of the disease did not correlate significantly with truncating and non-truncating mutations or N-terminal and C-terminal PHEX mutations. This study provides a comprehensive description of the clinical profiles, circulating levels of iFGF23 and gene mutation features of patients with XLH, further enriching the genotypic spectrum of the diseases. The findings show no evident correlation of circulating iFGF23 levels with the age or disease severity in patients with XLH.
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Affiliation(s)
- Xiaoyun Lin
- Shanghai Clinical Research Center of Bone Diseases, Department of Osteoporosis and Bone Diseases, Shanghai Sixth People's Hospital Affiliated to Shanghai Jiao Tong University, Shanghai, China
| | - Shanshan Li
- Shanghai Clinical Research Center of Bone Diseases, Department of Osteoporosis and Bone Diseases, Shanghai Sixth People's Hospital Affiliated to Shanghai Jiao Tong University, Shanghai, China
| | - Zhenlin Zhang
- Shanghai Clinical Research Center of Bone Diseases, Department of Osteoporosis and Bone Diseases, Shanghai Sixth People's Hospital Affiliated to Shanghai Jiao Tong University, Shanghai, China
| | - Hua Yue
- Shanghai Clinical Research Center of Bone Diseases, Department of Osteoporosis and Bone Diseases, Shanghai Sixth People's Hospital Affiliated to Shanghai Jiao Tong University, Shanghai, China
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Brener A, Lebenthal Y, Cleper R, Kapusta L, Zeitlin L. Body composition and cardiometabolic health of pediatric patients with X-linked hypophosphatemia (XLH) under burosumab therapy. Ther Adv Endocrinol Metab 2021; 12:20420188211001150. [PMID: 33796255 PMCID: PMC7970173 DOI: 10.1177/20420188211001150] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Accepted: 02/12/2021] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND Burosumab, a recombinant anti-FGF23 monoclonal antibody, was recently introduced as a treatment for X-linked hypophosphatemia (XLH). Burosumab normalizes blood phosphate levels, thereby healing rickets, decreasing leg bowing, and reducing pain. We aimed to explore the body composition and cardiometabolic health of pediatric patients with XLH treated with burosumab. METHODS This observational real-life study was conducted on growing children and adolescents. The outcome measures included changes in sex- and age-adjusted anthropometric and body composition parameters [fat mass (FM), fat-free mass (FFM), appendicular skeletal muscle mass (ASMM), muscle-to-fat ratio (MFR)], blood pressure, laboratory evaluation, and radiographic rickets severity [Thacher Rickets Severity Score (TRSS)]. Body composition was assessed by bioelectrical impedance analysis (BIA). Percentiles for FFM% and ASMM% were calculated according to BIA pediatric reference curves. The delta variable was calculated as the variable at 12 months minus the variable at baseline. RESULTS A total of 15 pediatric patients with XLH are treated in our clinic; included in the analyses were 7 children and adolescents (3 males, mean age 8.7 ± 3.2 years) with XLH without comorbidities. Baseline BIA revealed an unfavorable physique, with increased body fat percentage in five patients and decreased muscle mass in six. Indices of lean body mass significantly increased after 6 and 12 months of treatment: FFM(kg) (p = 0.001, p = 0.046, respectively) and ASMM(kg) (p = 0.012, p = 0.034, respectively), without any significant change in FM(kg). The percentile of ASMM% increased significantly after 6 months of treatment (p = 0.006) and stabilized thereafter. TRSS improved significantly after 12 months of therapy (p = 0.005). Age was positively correlated with delta TRSS (r = 0.814, p = 0.026), and delta TRSS was negatively correlated with delta MFR (r = -0.826, p = 0.022). CONCLUSIONS There was a heretofore unrecognized improvement in body composition of growing children and adolescents with XLH who were treated with burosumab. These findings highlight the need to initiate burosumab treatment at a younger age when rickets is less severe.
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Affiliation(s)
| | - Yael Lebenthal
- Pediatric Endocrinology and Diabetes Unit,
Dana-Dwek Children’s Hospital, Tel Aviv Sourasky Medical Center, Tel Aviv,
Israel; Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv,
Israel
| | - Roxana Cleper
- Pediatric Nephrology Unit, Dana-Dwek Children’s
Hospital, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel
- Sackler Faculty of Medicine, Tel Aviv
University, Tel Aviv, Israel
| | - Livia Kapusta
- Pediatric Cardiology Unit, Dana-Dwek Children’s
Hospital, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel
- Sackler Faculty of Medicine, Tel Aviv
University, Tel Aviv, Israel
- Department of Paediatric Cardiology, Amalia
Children’s Hospital, Radboud University Medical Centre, Nijmegen, The
Netherlands
| | - Leonid Zeitlin
- Pediatric Orthopedic Department, Dana-Dwek
Children’s Hospital, Tel Aviv Sourasky Medical Center, Tel Aviv,
Israel
- Sackler Faculty of Medicine, Tel Aviv
University, Tel Aviv, Israel
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18
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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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