1
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Poon KS, Tan KML, Zacharin M, Ho CWL. A De Novo Mosaic PHEX Variant Causing Sporadic X-Linked Hypophosphatemic Rickets in a 2-Year-Old Girl. J Pediatr Genet 2023; 12:308-311. [PMID: 38162152 PMCID: PMC10756725 DOI: 10.1055/s-0041-1728746] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Accepted: 03/11/2021] [Indexed: 10/21/2022]
Abstract
Pathogenic variants in the PHEX gene are causative of X-linked hypophosphatemic rickets (XLH). We present a case of a 2-year-old girl with hypophosphatemic rickets with genu varum and short stature without any family history of XLH. Next generation sequencing of the PHEX gene identified a splice donor variant, NM_000444.6:c.1173 + 5G > A in intron 10. This variant had a mosaic pattern with only 22% of the sequence reads showing the variant allele and was not present in the girl's parents, both of whom had a normal phenotype. This is a sporadic case of a de novo mosaic splice-site variant in the PHEX gene.
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Affiliation(s)
- Kok-Siong Poon
- Department of Laboratory Medicine, National University Hospital, Singapore
| | - Karen Mei-Ling Tan
- Department of Laboratory Medicine, National University Hospital, Singapore
| | - Margaret Zacharin
- Department of Hormone Research, Murdoch Children's Research Institute, Melbourne, Australia
- Department of Paediatrics, University of Melbourne, Victoria, Australia
- Department of Endocrinology & Diabetes, The Royal Children's Hospital, Melbourne, Victoria, Australia
| | - Cindy Wei-Li Ho
- Department of Paediatrics, Khoo Teck Puat - National University Children's Medical Institute, National University Health System, Singapore
- Department of Paediatrics, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
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2
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Terracciano A, De Bernardi ML, Novizio R, De Brasi D, Iolascon A, Della Monica M, Scavuzzo F, Serino D, Novelli A, Piscopo C. A New de novo Mosaic Mutation of PHEX Gene: A Case Report of a Boy with Hypophosphatemic Rickets. Endocr Metab Immune Disord Drug Targets 2023; 23:1235-1239. [PMID: 36847234 PMCID: PMC10518859 DOI: 10.2174/1871530323666230227142202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2022] [Revised: 12/28/2022] [Accepted: 01/03/2023] [Indexed: 03/01/2023]
Abstract
BACKGROUND X-linked hypophosphatemia is the most prevalent form of heritable rickets, characterized by an X-linked dominant inheritance pattern. The genetic basis of X-linked hypophosphatemia is a loss-of-function mutation in the PHEX gene (Phosphate regulating gene with Homology to Endopeptidases on the X chromosome), which leads to an enhanced production of phosphaturic hormone FGF23. X-linked hypophosphatemia causes rickets in children and osteomalacia in adults. Clinical manifestations are numerous and variable, including slowdown in growth, swing-through gait and progressive tibial bowing, related to skeletal and extraskeletal actions of FGF23. PHEX gene spans over 220 kb and consists of 22 exons. To date, hereditary and sporadic mutations are known (missense, nonsense, deletions and splice site mutations). CASE PRESENTATION Herein, we describe a male patient carrying a novel de novo mosaic nonsense mutation c.2176G>T (p.Glu726Ter) located in exon 22 of PHEX gene. CONCLUSION We highlight this new mutation among possible causative of X-linked hypophosphatemia and suggest that mosaicism of PHEX mutations is not so uncommon and should be excluded in diagnostic workflow of heritable rickets both in male and female patients.
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Affiliation(s)
- Alessandra Terracciano
- Translational Cytogenomics Research Unit, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | | | | | | | - Achille Iolascon
- Department of Molecular Medicine and Medical Biotechnology, University Federico II, Naples, Italy
| | | | | | | | - Antonio Novelli
- Translational Cytogenomics Research Unit, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | - Carmelo Piscopo
- Medical and Laboratory Genetic Unit, Cardarelli Hospital, Naples, Italy
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3
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Chen J, Sun J, Li X, Du M. Identification and functional characterization of a novel homozygous intronic variant in the fumarylacetoacetate hydrolase gene in a Chinese patient with tyrosinemia type 1. BMC Med Genomics 2022; 15:251. [PMID: 36463171 PMCID: PMC9719145 DOI: 10.1186/s12920-022-01406-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Accepted: 11/29/2022] [Indexed: 12/05/2022] Open
Abstract
BACKGROUND Hereditary tyrosinemia type 1 (HT1; OMIM# 276700) is a genetic metabolism disorder caused by disease-causing variants in the fumarylacetoacetate hydrolase (FAH) gene encoding the last enzyme of the tyrosine catabolic pathway. Herein, we describe the clinical features and genetic characteristics of HT1 in a five years and seven months old Chinese patient. METHODS After clinical diagnosis of the proband with HT1, genetic testing was performed by Sanger sequencing of the FAH gene in all family members. Functional analysis of the disease-causing variant was performed by cDNA sequencing to understand the effect of the variant on FAH transcript. To further predict the variant effect, we used Human Splicing Finder (HSF) and PyMol in silico analysis. RESULTS We identified a novel previously undescribed intronic variant in the FAH gene (c.914-1G>A). It was detected in a child who was homozygous for the variant and had the clinical presentation of HT1. cDNA sequencing showed that this splice-junction variant affected the transcription of FAH by formation of two different transcripts. Our observations and laboratory experiments were in line with in silico methods. CONCLUSIONS Our study provides new insight into the HT1 variant spectrum and a better understanding of this disease in the Chinese population. This will be useful for molecular diagnosis in our country in cases where premarital screening, prenatal diagnosis and preimplantation genetic diagnosis are planned.
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Affiliation(s)
- Jiao Chen
- grid.479690.50000 0004 1789 6747Department of Medical Genetics and Prenatal Diagnosis, Taizhou People’s Hospital, Taizhou, China
| | - Junhui Sun
- grid.414906.e0000 0004 1808 0918Reproductive Medicine Center, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China
| | - Xuefang Li
- grid.479690.50000 0004 1789 6747Department of Medical Genetics and Prenatal Diagnosis, Taizhou People’s Hospital, Taizhou, China
| | - Mengmeng Du
- grid.479690.50000 0004 1789 6747Department of Medical Genetics and Prenatal Diagnosis, Taizhou People’s Hospital, Taizhou, China
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4
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Pathogenic Variants of the PHEX Gene. ENDOCRINES 2022. [DOI: 10.3390/endocrines3030040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [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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5
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Collins MT, Marcucci G, Anders HJ, Beltrami G, Cauley JA, Ebeling PR, Kumar R, Linglart A, Sangiorgi L, Towler DA, Weston R, Whyte MP, Brandi ML, Clarke B, Thakker RV. Skeletal and extraskeletal disorders of biomineralization. Nat Rev Endocrinol 2022; 18:473-489. [PMID: 35578027 DOI: 10.1038/s41574-022-00682-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 04/13/2022] [Indexed: 12/15/2022]
Abstract
The physiological process of biomineralization is complex and deviation from it leads to a variety of diseases. Progress in the past 10 years has enhanced understanding of the genetic, molecular and cellular pathophysiology underlying these disorders; sometimes, this knowledge has both facilitated restoration of health and clarified the very nature of biomineralization as it occurs in humans. In this Review, we consider the principal regulators of mineralization and crystallization, and how dysregulation of these processes can lead to human disease. The knowledge acquired to date and gaps still to be filled are highlighted. The disorders of mineralization discussed comprise a broad spectrum of conditions that encompass bone disorders associated with alterations of mineral quantity and quality, as well as disorders of extraskeletal mineralization (hyperphosphataemic familial tumoural calcinosis). Included are disorders of alkaline phosphatase (hypophosphatasia) and phosphate homeostasis (X-linked hypophosphataemic rickets, fluorosis, rickets and osteomalacia). Furthermore, crystallopathies are covered as well as arterial and renal calcification. This Review discusses the current knowledge of biomineralization derived from basic and clinical research and points to future studies that will lead to new therapeutic approaches for biomineralization disorders.
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Affiliation(s)
- Michael T Collins
- Skeletal Disorders and Mineral Homeostasis Section, National Institute of Dental and Craniofacial Research, NIH, Bethesda, MD, USA.
| | - Gemma Marcucci
- Bone Metabolic Diseases Unit, Department of Biomedical, Experimental and Clinical Sciences, University of Florence, Florence, Italy
| | - Hans-Joachim Anders
- Department of Medicine IV, Hospital of the University of Munich, Ludwig-Maximilians University, Munich, Germany
| | - Giovanni Beltrami
- Department Paediatric Orthopedic Oncology, Careggi and Meyer Children Hospital, Florence, Italy
| | - Jane A Cauley
- Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA, USA
| | - Peter R Ebeling
- Department of Medicine, School of Clinical Sciences, Monash University, Melbourne, Australia
| | - Rajiv Kumar
- Departments of Medicine, Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN, USA
| | - Agnès Linglart
- APHP, Endocrinologie et diabète de l'enfant, Paris, France
| | - Luca Sangiorgi
- Medical Genetics and Skeletal Rare Diseases, IRCCS Istituto Ortopedico Rizzoli, Bologna, Italy
| | - Dwight A Towler
- University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Ria Weston
- Cardiovascular Research Group, Manchester Metropolitan University, Manchester, UK
| | - Michael P Whyte
- Center for Metabolic Bone Disease and Molecular Research, Shriners Hospitals for Children-St Louis, St Louis, MO, USA
- Division of Bone and Mineral Diseases, Department of Internal Medicine, Washington University School of Medicine, St Louis, MO, USA
| | | | - Bart Clarke
- Mayo Clinic Division of Endocrinology, Diabetes, Metabolism, and Nutrition, Rochester, MN, USA
| | - Rajesh V Thakker
- Academic Endocrine Unit, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
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6
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Lin Y, Zhang W, Huang X, Su L, Cai Y, Liang C, Rao M, Liu L, Zeng C. Two De Novo Mosaic Variants Within the Same Site of PHEX Gene in a Girl with X-Linked Hypophosphatemic Rickets. Calcif Tissue Int 2022; 110:266-271. [PMID: 34487203 DOI: 10.1007/s00223-021-00909-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Accepted: 08/22/2021] [Indexed: 10/20/2022]
Abstract
X-linked hypophosphatemic rickets (XLH) is the most common form of hypophosphatemic rickets, which is caused by the deficiencies of PHEX gene with an X-linked dominant inheritance pattern. As at least several thousands of XLH patients have been diagnosed, only several males and fewer females with mosaicism of PHEX gene were found. Here we describe an XLH girl with two de novo mosaic variants within the same site of PHEX gene. To rapidly screen all of the causative genes of hypophosphatemic rickets and rule out other diseases, DNA samples were initially analyzed using whole exome sequencing (WES). Interestingly, two different pathogenic mosaic variants, a known c.1809G > A(p.W603*) variant and a novel c.1809G > T(p.W603C) variant within the same site of PHEX gene, were identified in the proband by WES. Subsequent Sanger sequencing confirmed the presence and de novo pattern of these two mosaic variants in the proband, which were absent in her healthy parents. This is the first case to report two different mosaic variants of PHEX gene in an XLH individual. This XLH girl has a de novo mosaic genotype of c.1809 = /G > T/G > A in PHEX gene. Our report adds an unusual mocaicism case for XLH and expands the mutational event and spectrum of PHEX gene. Our report also alerts clinicians and geneticists to be cautious about mocaicism and detection methods.
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Affiliation(s)
- Yunting Lin
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 9 Jinsui Rd., Guangzhou, 510623, China
| | - Wen Zhang
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 9 Jinsui Rd., Guangzhou, 510623, China
| | - Xinjiang Huang
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 9 Jinsui Rd., Guangzhou, 510623, China
| | - Ling Su
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 9 Jinsui Rd., Guangzhou, 510623, China
| | - Yanna Cai
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 9 Jinsui Rd., Guangzhou, 510623, China
| | - Cuili Liang
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 9 Jinsui Rd., Guangzhou, 510623, China
| | - Min Rao
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 9 Jinsui Rd., Guangzhou, 510623, China
| | - Li Liu
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 9 Jinsui Rd., Guangzhou, 510623, China.
| | - Chunhua Zeng
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 9 Jinsui Rd., Guangzhou, 510623, China.
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7
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Asano S, Sako S, Funasaki Y, Takeshita Y, Niida Y, Takamura T. A mosaic mutation of phosphate-regulating gene with homologies to endopeptidases on the X chromosome (PHEX) in X-linked hypophosphatemic rickets with mild bone phenotypes. Endocr J 2021; 68:1135-1141. [PMID: 33907069 DOI: 10.1507/endocrj.ej20-0809] [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: 11/23/2022] Open
Abstract
X-linked hypophosphatemic rickets (XLH) is primarily characterized by renal phosphate wasting with hypophosphatemia, short stature, and bone deformity of the leg. Here we present a male case of XLH with relatively mild bone deformity caused by a mosaic mutation of the phosphate-regulating gene with homologies to endopeptidases on the X chromosome (PHEX). Polymerase chain reaction (PCR) direct sequencing revealed a novel in-frame deletion, NM-000444.6:c.671-685del p.Gln224-Ser228del, at exon 6 in PHEX as a mosaic pattern. This mutation was not found in any database and may result in a significant change in higher-order protein structure and function. TA cloning of the PCR product and clone sequencing estimated the mutation allele frequency at 21%. Literature review of the previously reported three cases with novel mosaic mutations in PHEX, together with the present case, suggests that the rates of the mutation allele correlate with phenotype severity to some extent. We initially treated him with nutritional vitamin D supplements and phosphate salts. However, to avoid the development of secondary/tertiary hyperparathyroidism, we had switched nutritional to active vitamin D supplementation with reduced phosphorus salts. The present report contributes to understanding the relationship between the mosaic rate, in addition to the mutation locus, of the PHEX gene, and clinical features of XLH.
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Affiliation(s)
- Shoko Asano
- Department of Endocrinology and Metabolism, Kanazawa University Graduate School of Medical Sciences, Ishikawa 920-8640, Japan
| | - Saori Sako
- Department of Endocrinology and Metabolism, Kanazawa University Graduate School of Medical Sciences, Ishikawa 920-8640, Japan
| | - Yuka Funasaki
- Department of Endocrinology and Metabolism, Kanazawa University Graduate School of Medical Sciences, Ishikawa 920-8640, Japan
| | - Yumie Takeshita
- Department of Endocrinology and Metabolism, Kanazawa University Graduate School of Medical Sciences, Ishikawa 920-8640, Japan
| | - Yo Niida
- Division of Genomic Medicine, Department of Advanced Medicine, Medical Research Institute, Kanazawa Medical University, Ishikawa 920-0293, Japan
| | - Toshinari Takamura
- Department of Endocrinology and Metabolism, Kanazawa University Graduate School of Medical Sciences, Ishikawa 920-8640, Japan
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8
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Lin Y, Xu J, Li X, Sheng H, Su L, Wu M, Cheng J, Huang Y, Mao X, Zhou Z, Zhang W, Li C, Cai Y, Wu D, Lu Z, Yin X, Zeng C, Liu L. Novel variants and uncommon cases among southern Chinese children with X-linked hypophosphatemia. J Endocrinol Invest 2020; 43:1577-1590. [PMID: 32253725 DOI: 10.1007/s40618-020-01240-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Accepted: 03/24/2020] [Indexed: 12/17/2022]
Abstract
PURPOSE X-linked hypophosphatemia (XLH) is the most common inherited renal phosphate wasting disorder and is often misdiagnosed as vitamin D deficiency. This study aims to provide clinical and mutational characteristics of 65 XLH pediatric patients in southern China. METHODS In this work, a combination of DNA sequencing and qPCR analysis was used to study the PHEX gene in 80 pediatric patients diagnosed with hypophosphatemia. The clinical and laboratory data of confirmed 65 XLH patients were assessed and analyzed retrospectively. RESULTS In 65 XLH patients from 61 families, 51 different variants in the PHEX gene were identified, including 23 previously reported variants and 28 novel variants. In this cohort of XLH patients, the c.1601C>T(p.Pro534Leu) variant appears more frequently. Fourteen uncommon XLH cases were described, including four boys with de novo mosaic variants, eight patients with large deletions and a pair of monozygotic twins. The clinical manifestations in this cohort are very similar to those previously reported. CONCLUSION This study extends the mutational spectrum of the PHEX gene, which will contribute to accurate diagnosis. This study also suggests a supplementary qPCR or MLPA assay may be performed along with classical sequencing to confirm the gross insertion/deletion.
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Affiliation(s)
- Y Lin
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 9 Jinsui Rd., Guangzhou, 510623, China
| | - J Xu
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 9 Jinsui Rd., Guangzhou, 510623, China
| | - X Li
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 9 Jinsui Rd., Guangzhou, 510623, China
| | - H Sheng
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 9 Jinsui Rd., Guangzhou, 510623, China
| | - L Su
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 9 Jinsui Rd., Guangzhou, 510623, China
| | - M Wu
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 9 Jinsui Rd., Guangzhou, 510623, China
| | - J Cheng
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 9 Jinsui Rd., Guangzhou, 510623, China
| | - Y Huang
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 9 Jinsui Rd., Guangzhou, 510623, China
| | - X Mao
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 9 Jinsui Rd., Guangzhou, 510623, China
| | - Z Zhou
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 9 Jinsui Rd., Guangzhou, 510623, China
| | - W Zhang
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 9 Jinsui Rd., Guangzhou, 510623, China
| | - C Li
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 9 Jinsui Rd., Guangzhou, 510623, China
| | - Y Cai
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 9 Jinsui Rd., Guangzhou, 510623, China
| | - D Wu
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 9 Jinsui Rd., Guangzhou, 510623, China
| | - Z Lu
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 9 Jinsui Rd., Guangzhou, 510623, China
| | - X Yin
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 9 Jinsui Rd., Guangzhou, 510623, China
| | - C Zeng
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 9 Jinsui Rd., Guangzhou, 510623, China.
| | - L Liu
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 9 Jinsui Rd., Guangzhou, 510623, China.
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9
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Zheng B, Wang C, Chen Q, Che R, Sha Y, Zhao F, Ding G, Zhou W, Jia Z, Huang S, Chen Y, Zhang A. Functional Characterization of PHEX Gene Variants in Children With X-Linked Hypophosphatemic Rickets Shows No Evidence of Genotype-Phenotype Correlation. J Bone Miner Res 2020; 35:1718-1725. [PMID: 32329911 DOI: 10.1002/jbmr.4035] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Revised: 03/16/2020] [Accepted: 03/20/2020] [Indexed: 11/08/2022]
Abstract
X-linked hypophosphatemia (XLHR) is caused by loss-of-function mutations in the phosphate regulating endopeptidase homolog X-linked (PHEX) gene. Considerable controversy exists regarding genotype-phenotype correlations in XLHR. The present study describes the clinical features and molecular genetic bases of 53 pediatric patients with XLHR. Overall, 47 different mutations were identified, of which 27 were not previously described in the literature or entered in the Human Gene Mutation Database (HGMD). A high prevalence (72.34%) of truncating variants was observed in XLHR patients. The clinical presentation and severity of XLHR did not show an evident correlation between the truncating and non-truncating mutation types in our cohort. To further delineate the characteristics of PHEX variants underlying this nonsignificant trend, we assessed the effects of 10 PHEX variants on protein expression, cellular trafficking, and endopeptidase activity. Our results showed that the nonsense mutations p.Arg567*, p.Gln714*, and p.Arg747* caused a reduction of protein molecular weight and a trafficking defect. Among seven non-truncating mutations, the p.Cys77Tyr, p.Cys85Ser, p.Ile281Lys, p.Ile333del, p.Ala514Pro, and p.Gly572Ser mutants were not secreted into the medium and remained trapped inside cells in an immature form, whereas the p.Gly553Glu mutant was terminally glycosylated and secreted into the medium. We further assessed the endopeptidase activity of the p.Gly553Glu mutant using a quenched fluorogenic peptide substrate and revealed that the activity of p.Gly553Glu significantly reduced to 13% compared with the wild type, which indicated disruption of catalytic function. These data not only support the clinical results showing no correlation between disease severity and the type of PHEX mutation but also provide helpful molecular insights into the pathogenesis of XLHR. © 2020 American Society for Bone and Mineral Research.
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Affiliation(s)
- Bixia Zheng
- Nanjing Key Laboratory of Pediatrics, Children's Hospital of Nanjing Medical University, Nanjing, China
| | - Chunli Wang
- Nanjing Key Laboratory of Pediatrics, Children's Hospital of Nanjing Medical University, Nanjing, China
| | - Qiuxia Chen
- Department of Nephrology, Children's Hospital of Nanjing Medical University, Nanjing, China
| | - Ruochen Che
- Department of Nephrology, Children's Hospital of Nanjing Medical University, Nanjing, China
| | - Yugen Sha
- Department of Nephrology, Children's Hospital of Nanjing Medical University, Nanjing, China
| | - Fei Zhao
- Department of Nephrology, Children's Hospital of Nanjing Medical University, Nanjing, China
| | - Guixia Ding
- Department of Nephrology, Children's Hospital of Nanjing Medical University, Nanjing, China
| | - Wei Zhou
- Nanjing Key Laboratory of Pediatrics, Children's Hospital of Nanjing Medical University, Nanjing, China
| | - Zhanjun Jia
- Nanjing Key Laboratory of Pediatrics, Children's Hospital of Nanjing Medical University, Nanjing, China
| | - Songming Huang
- Department of Nephrology, Children's Hospital of Nanjing Medical University, Nanjing, China.,Jiangsu Key Laboratory of Pediatrics, Nanjing Medical University, Nanjing, China
| | - Ying Chen
- Department of Nephrology, Children's Hospital of Nanjing Medical University, Nanjing, China
| | - Aihua Zhang
- Department of Nephrology, Children's Hospital of Nanjing Medical University, Nanjing, China.,Jiangsu Key Laboratory of Pediatrics, Nanjing Medical University, Nanjing, China
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10
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Sun J, Zhou Z, Weng C, Wang C, Chen J, Feng X, Yu P, Qi M. Identification and functional characterization of a hemizygous novel intronic variant in OCRL gene causes Lowe syndrome. Clin Exp Nephrol 2020; 24:657-665. [PMID: 32394213 DOI: 10.1007/s10157-020-01897-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Accepted: 04/23/2020] [Indexed: 10/24/2022]
Abstract
BACKGROUND Lowe syndrome is an X-linked multisystem disorder affecting eyes, nervous system, and kidney. The main causes are mutations in the OCRL gene that encodes a member of the inositol polyphosphate-5-phosphatase protein family. In this study, we aimed to gain new insights into the consequences of a novel OCRL intronic variant on pre-mRNA splicing as a main cause of Lowe syndrome in a boy. METHODS After clinical diagnosis of the patient with Lowe syndrome, genetic testing was used to detect the presence of the OCRL variants. In silico analysis, human splicing finder and PyMol were used to predict this variant effect. Then, we analyzed the variant transcript by using a minigene construct in addition to in silico analysis. RESULTS A hemizygous novel splicing variant in the intron 10 splice donor site of OCRL (c.939 + 3A > C) was identified in a boy with Lowe syndrome. We detected that the splice junction variant leads to aberrant OCRL mRNA splicing which results in the formation of an alternative transcript in which 29 nucleotides of exon 10 were skipped. The findings obtained from the exon-trapping assay were identical to those of in silico analysis. Hence, the truncated OCRL protein may lacked the last 597 native amino acids. CONCLUSIONS The minigene assays detected the same transcript abnormality to in silico assay and were reliable in revealing the pathogenicity of the intronic variant we have used previously. Overall, this study provides new insights about Lowe syndrome and further reveals the molecular pathogenicity mechanism of the intronic variant disease.
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Affiliation(s)
- Junhui Sun
- Department of Cell Biology and Medical Genetics, School of Medicine, Zhejiang University, Research Building A713, Yuhangtang Road 866, Hangzhou, China.,Zhejiang California International Nanosystems Institute, Zhjiang University, Hangzhou, China
| | - Zhongwei Zhou
- Department of Cell Biology and Medical Genetics, School of Medicine, Zhejiang University, Research Building A713, Yuhangtang Road 866, Hangzhou, China
| | - Chen Weng
- Department of Cell Biology and Medical Genetics, School of Medicine, Zhejiang University, Research Building A713, Yuhangtang Road 866, Hangzhou, China
| | - Chaojun Wang
- Department of Urology, The First Affiliated Hospital of Zhejiang University, Hangzhou, China
| | - Jiao Chen
- Department of Cell Biology and Medical Genetics, School of Medicine, Zhejiang University, Research Building A713, Yuhangtang Road 866, Hangzhou, China
| | - Xue Feng
- Department of Cell Biology and Medical Genetics, School of Medicine, Zhejiang University, Research Building A713, Yuhangtang Road 866, Hangzhou, China
| | - Ping Yu
- Department of Cell Biology and Medical Genetics, School of Medicine, Zhejiang University, Research Building A713, Yuhangtang Road 866, Hangzhou, China
| | - Ming Qi
- Department of Cell Biology and Medical Genetics, School of Medicine, Zhejiang University, Research Building A713, Yuhangtang Road 866, Hangzhou, China. .,Zhejiang California International Nanosystems Institute, Zhjiang University, Hangzhou, China. .,Center for Genetic and Genomic Medicine First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China. .,Department of Pathology and Laboratory of Medicine, University of Rochester Medical Centre, Rochester, NY, USA. .,DIAN Diagnostics, Hangzhou, China.
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11
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Zhao Y, Yang F, Wang L, Che H. Familial hypophosphatemic rickets caused by a PHEX gene mutation accompanied by a NPR2 missense mutation. J Pediatr Endocrinol Metab 2020; 33:305-311. [PMID: 31927522 DOI: 10.1515/jpem-2019-0380] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Accepted: 11/29/2019] [Indexed: 01/10/2023]
Abstract
Background Familial hypophosphatemic rickets, which is usually acknowledged as X-linked hypophosphatemic rickets (XLH), is a rare hereditary disease. XLH caused by mutations in the PHEX gene often manifests as growth retardation, skeletal deformities, osteodynia and dental dysplasia. NPR2 mutations are reported to cause disproportionate short stature. Our study was designed to identify the gene mutations of three patients in one family. Case description A 40-year-old Chinese male visited the hospital for continuous osteodynia and presented with bilateral leg bowing, absent teeth and a progressive limp. The age of onset was approximately 2 years old. His 63-year-old mother and 42-year-old brother both shared identical symptoms with him. The laboratory tests were consistent with XLH, which showed decreased levels of blood phosphorus and 1,25-dihydroxyvitamin D3 as well as increased urinary phosphorus excretion. Mutation analysis revealed that the proband as well as his mother and his brother all had a PHEX mutation in exon 14 (c.1543C > T), and the proband also had a NPR2 mutation in exon 21 (c.3058C > T). Conclusions We report the familial hypophosphatemic rickets of three patients in a Chinese family caused by a PHEX gene mutation in exon 14 (c.1543C > T), which had never been reported in Chinese patients. We first report an XLH case together with a NPR2 mutation that had never been reported before.
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Affiliation(s)
- Yongting Zhao
- Department of Endocrinology, The Second Affiliated Hospital of Harbin Medical University, Harbin, P.R. China
| | - Fan Yang
- Department of Endocrinology, Drum Tower Hospital Affiliated to Nanjing University Medical School, Nanjing, China
| | - Lihong Wang
- Department of Endocrinology, The Second Affiliated Hospital of Harbin Medical University, Harbin, P.R. China.,Translational Medicine Research and Cooperation Center of Northern China, Heilongjiang Academy of Medical Sciences, Harbin, China
| | - Hui Che
- Translational Medicine Research and Cooperation Center of Northern China, Heilongjiang Academy of Medical Sciences, Harbin, China
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12
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BinEssa HA, Zou M, Al-Enezi AF, Alomrani B, Al-Faham MSA, Al-Rijjal RA, Meyer BF, Shi Y. Functional analysis of 22 splice-site mutations in the PHEX, the causative gene in X-linked dominant hypophosphatemic rickets. Bone 2019; 125:186-193. [PMID: 31102713 DOI: 10.1016/j.bone.2019.05.017] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Revised: 04/24/2019] [Accepted: 05/13/2019] [Indexed: 12/19/2022]
Abstract
CONTEXT X-linked hypophosphatemic rickets (XLH) is caused by inactivating mutations in the PHEX gene and is the most common form of hereditary rickets. The splice-site mutations account for 17% of all reported PHEX mutations. The functional consequence of these splice-site mutations has not been systemically investigated. OBJECTIVE The current study was undertaken to functionally annotate previously reported 22 splice-site mutations in the PHEX gene. METHODS PHEX mini-genes with different splice-site mutations were created by site-directed mutagenesis and expressed in HEK293 cells. The mRNA transcripts were analyzed by RT-PCR, cloning, and sequencing. RESULTS These splicing mutations led to a variety of consequences, including exon skipping, intron retention, and activation of cryptic splice sites. Among 22 splice-site mutations, exon skipping was the most common event accounting for 73% (16/22). Non-canonical splice-site mutations could result in splicing errors to the same extent as canonical splice-site mutations such as c.436+3G>C, c.436+4A>C, c.436+6T>C, c.437-3C>G, c.850-3C>G, c.1080-3C>A, c.1482+5G>C, c.1586+6T>C, c.1645+5G>A, c.1645+6T>C, c.1701-16T>A, c.1768+5G>A, and c.1899+5G>A. Interestingly, non-canonical (c.436+6T>C and c.1586+6T>C) and canonical splice-site mutations (c.1769-1G>C) could generate partial splicing errors (both wild-type and mutant transcripts were detected), resulting in incomplete inactivation of PHEX gene, which may explain the mild disease phenotype reported previously, providing evidence of genotype-phenotype correlation. c.1645C>T (p.R549*) had no impact on pre-mRNA splicing although it is located next to canonical splice donor site GT. CONCLUSIONS Exon skipping is the most common outcome due to splice-site mutations. Both canonical and non-canonical splice-site mutations can result in either severe or mild RNA splicing defects, contributing to phenotype heterogeneity. Non-canonical splice-site mutations should not be overlooked in genetic screening especially those located within 50 bp from canonical splice site.
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Affiliation(s)
- Huda A BinEssa
- Department of Genetics, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia
| | - Minjing Zou
- Department of Genetics, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia
| | - Anwar F Al-Enezi
- Department of Genetics, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia
| | - Basma Alomrani
- Department of Genetics, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia
| | - Manar S A Al-Faham
- Department of Genetics, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia
| | - Roua A Al-Rijjal
- Department of Genetics, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia
| | - Brian F Meyer
- Department of Genetics, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia
| | - Yufei Shi
- Department of Genetics, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia.
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13
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Zhang C, Zhao Z, Sun Y, Xu L, JiaJue R, Cui L, Pang Q, Jiang Y, Li M, Wang O, He X, He S, Nie M, Xing X, Meng X, Zhou X, Yan L, Kaplan JM, Insogna KL, Xia W. Clinical and genetic analysis in a large Chinese cohort of patients with X-linked hypophosphatemia. Bone 2019; 121:212-220. [PMID: 30682568 DOI: 10.1016/j.bone.2019.01.021] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Revised: 01/11/2019] [Accepted: 01/20/2019] [Indexed: 01/09/2023]
Abstract
X-linked Hypophosphatemia (XLH) is caused by loss of function mutations in the PHEX gene. Given the recent availability of a new therapy for XLH, a retrospective analysis of the most recent 261 Chinese patients with XLH evaluated at Peking Union Medical College Hospital was conducted. Clinical, biochemical, radiographic studies, as well as genetic analyses, including Sanger sequencing for point mutations and Multiplex Ligation-dependent Probe Amplification (MLPA) to detect large deletions/duplications were employed. Based on the structure of Neprilysin (NEP), a member of M13 family that includes PHEX, a three-dimensional (3D) model of PHEX was constructed, missense and nonsense mutations were positioned on the predicted structure to visualize relative positions of these two types of variants. Sex differences and genotype-phenotype correlations were also undertaken. Genetic analyses identified 166 PHEX mutations in 261 XLH patients. One hundred and eleven of the 166 mutations were unreported. Four mutational 'hot-spots' were identified in this cohort (P534L, G579R, R747X, c.1645+1 G>A). Missense mutations, but not nonsense mutations, clustered in the two putative lobes of the PHEX protein, suggesting these are functionally important regions of the molecule. Circulating levels of intact FGF23 were significantly elevated (median level 101.9 pg/mL; reference range 16.1-42.2 pg/mL). No significant sex differences, as well as no phenotypic differences were identified between patients with putative truncating and non-truncating PHEX mutations. However, patients with N-terminal PHEX mutations had an earlier age of onset of disease (P = 0.015) and higher iFGF23 levels (P = 0.045) as compared to those with C-terminal mutations. These data provide a comprehensive characterization of the largest cohort of patients with XLH reported to date from China, which will help in evaluating the applicability of emerging therapies for this disease in this ethnic group.
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Affiliation(s)
- Cong Zhang
- Department of Endocrinology, Key Laboratory of Endocrinology, Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Shuaifuyuan No. 1, Wangfujing, Dongcheng District, Beijing 100730, China
| | - Zhen Zhao
- Department of Endocrinology, Key Laboratory of Endocrinology, Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Shuaifuyuan No. 1, Wangfujing, Dongcheng District, Beijing 100730, China; Department of Geriatrics, Beijing Friendship Hospital Affiliated to Capital Medical University, Beijing 100050, China
| | - Yue Sun
- Department of Endocrinology, Key Laboratory of Endocrinology, Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Shuaifuyuan No. 1, Wangfujing, Dongcheng District, Beijing 100730, China
| | - Lijun Xu
- Department of Endocrinology, Key Laboratory of Endocrinology, Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Shuaifuyuan No. 1, Wangfujing, Dongcheng District, Beijing 100730, China
| | - Ruizhi JiaJue
- Department of Endocrinology, Key Laboratory of Endocrinology, Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Shuaifuyuan No. 1, Wangfujing, Dongcheng District, Beijing 100730, China
| | - Lijia Cui
- Department of Endocrinology, Key Laboratory of Endocrinology, Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Shuaifuyuan No. 1, Wangfujing, Dongcheng District, Beijing 100730, China
| | - Qianqian Pang
- Department of Endocrinology, Key Laboratory of Endocrinology, Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Shuaifuyuan No. 1, Wangfujing, Dongcheng District, Beijing 100730, China
| | - Yan Jiang
- Department of Endocrinology, Key Laboratory of Endocrinology, Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Shuaifuyuan No. 1, Wangfujing, Dongcheng District, Beijing 100730, China
| | - Mei Li
- Department of Endocrinology, Key Laboratory of Endocrinology, Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Shuaifuyuan No. 1, Wangfujing, Dongcheng District, Beijing 100730, China
| | - Ou Wang
- Department of Endocrinology, Key Laboratory of Endocrinology, Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Shuaifuyuan No. 1, Wangfujing, Dongcheng District, Beijing 100730, China
| | - Xiaodong He
- Department of Endocrinology, Key Laboratory of Endocrinology, Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Shuaifuyuan No. 1, Wangfujing, Dongcheng District, Beijing 100730, China; Department of Endocrinology, The First Affiliated Hospital of Xinjiang Medical University, Urumqi 830054, China
| | - Shuli He
- Department of Endocrinology, Key Laboratory of Endocrinology, Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Shuaifuyuan No. 1, Wangfujing, Dongcheng District, Beijing 100730, China
| | - Min Nie
- Department of Endocrinology, Key Laboratory of Endocrinology, Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Shuaifuyuan No. 1, Wangfujing, Dongcheng District, Beijing 100730, China
| | - Xiaoping Xing
- Department of Endocrinology, Key Laboratory of Endocrinology, Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Shuaifuyuan No. 1, Wangfujing, Dongcheng District, Beijing 100730, China
| | - Xunwu Meng
- Department of Endocrinology, Key Laboratory of Endocrinology, Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Shuaifuyuan No. 1, Wangfujing, Dongcheng District, Beijing 100730, China
| | - Xueying Zhou
- Department of Endocrinology, Key Laboratory of Endocrinology, Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Shuaifuyuan No. 1, Wangfujing, Dongcheng District, Beijing 100730, China
| | - Lina Yan
- Department of Endocrinology, Baogang Hospital, Baotou, Inner Mongolia 014000, China
| | - Jared M Kaplan
- Department of Medicine, Section of Endocrinology, Yale School of Medicine, New Haven, CT, USA
| | - Karl L Insogna
- Department of Medicine, Section of Endocrinology, Yale School of Medicine, New Haven, CT, USA
| | - Weibo Xia
- Department of Endocrinology, Key Laboratory of Endocrinology, Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Shuaifuyuan No. 1, Wangfujing, Dongcheng District, Beijing 100730, China.
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14
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Yang M, Kim J, Yang A, Jang J, Jeon TY, Cho SY, Jin DK. A novel de novo mosaic mutation in PHEX in a Korean patient with hypophosphatemic rickets. Ann Pediatr Endocrinol Metab 2018; 23:229-234. [PMID: 30599486 PMCID: PMC6312911 DOI: 10.6065/apem.2018.23.4.229] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Revised: 03/17/2018] [Accepted: 06/17/2018] [Indexed: 11/24/2022] Open
Abstract
X-linked hypophosphatemic rickets is caused by loss-of-function mutations in PHEX, which encodes a phosphate-regulating endopeptidase homolog. We report a 26-year-old man with X-linked hypophosphatemic rickets who showed decreased serum phosphate accompanied by bilateral genu valgum and short stature. He had received medical treatment with vitamin D (alfacalcidol) and phosphate from the age of 3 to 20 years. He underwent surgery due to valgus deformity at the age of 14 and 15. Targeted gene panel sequencing for Mendelian genes identified a nonsense mutation in PHEX (c.589C>T; p.Gln197Ter) and a mosaic pattern where only 38% of sequence reads showed the variant allele. This mutation was not found in his mother, who had a normal phenotype. This is a case of a sporadic nonsense mutation in PHEX and up to date, this is the first case of a mosaic mutation in PHEX in Korea.
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Affiliation(s)
- Misun Yang
- Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Jinsup Kim
- Department of Pediatrics, Hanyang University Guri Hopistal, Hanyang University College of Medicine, Guri, Korea
| | - Aram Yang
- Department of Pediatrics, Inha University School of Medicine, Incheon, Korea
| | | | - Tae Yeon Jeon
- Department of Radiology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Sung Yoon Cho
- Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Dong-Kyu Jin
- Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
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15
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Abstract
Rickets refers to deficient mineralization at the growth plate and is usually associated with abnormal serum calcium and/or phosphate. There are several subtypes of rickets, including hypophosphatemic rickets (vitamin-D-resistant rickets secondary to renal phosphate wasting), vitamin D-dependent rickets (defects of vitamin D metabolism) and nutritional rickets (caused by dietary deficiency of vitamin D, and/or calcium, and/or phosphate). Most rickets manifest as bone deformities, bone pain, and impaired growth velocity. Diagnosis of rickets is established through the medical history, physical examination, biochemical tests and radiographs. It is of crucial importance to determine the cause of rickets, including the molecular characterization in case of vitamin D resistant rickets, and initiate rapidly the appropriate therapy. In this review, we describe the different causes and therapies of genetic and nutritional rickets, supported by the recent progress in genetics and development of novel molecules such as anti-FGF23 antibody.
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Affiliation(s)
- A S Lambert
- APHP, Department of Pediatric Endocrinology and Diabetology for Children, Bicêtre Paris-Sud, Le Kremlin-Bicêtre, France; APHP, Reference Center for Rare Disorders of Calcium and Phosphate Metabolism, Filière OSCAR and Plateforme D'Expertise Maladies Rares Paris-Sud, Bicêtre Paris-Sud, Le Kremlin Bicêtre, France.
| | - A Linglart
- APHP, Department of Pediatric Endocrinology and Diabetology for Children, Bicêtre Paris-Sud, Le Kremlin-Bicêtre, France; APHP, Reference Center for Rare Disorders of Calcium and Phosphate Metabolism, Filière OSCAR and Plateforme D'Expertise Maladies Rares Paris-Sud, Bicêtre Paris-Sud, Le Kremlin Bicêtre, France
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