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Wang LKP, Shanmugasundaram M, Cooney E, Lee PDK. Siblings with vitamin D-dependent rickets type 1A: Importance of genetic testing and a review of genotype-phenotype correlations. Am J Med Genet A 2024:e63780. [PMID: 38822637 DOI: 10.1002/ajmg.a.63780] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2024] [Revised: 05/09/2024] [Accepted: 05/18/2024] [Indexed: 06/03/2024]
Abstract
Vitamin D-dependent rickets type 1A (VDDR1A) is a rare condition caused by biallelic pathogenic variants in CYP27B1, which encodes 25-hydroxyvitamin D3-1-α-hydroxylase. Inadequate activity of this enzyme results in deficient 1α-hydroxylation of inactive 25-hydroxyvitamin D to biologically active 1,25-dihydroxyvitamin D, with consequent adverse effects on calcium and phosphate metabolism. A female child was clinically diagnosed at 18 months old with hypophosphatemic rickets based on phenotype and biochemical testing, with neither parent affected. A subsequent affected male sibling led to the reconsideration of the diagnosis. Exome sequencing showed a homozygous CYP27B1 c.1040T>A (p.Ile347Asn) variant for both children. No variants were found in genes associated with hypophosphatemic rickets. A review of published cases of VDDR1A with homozygous CYP27B1 variants indicates variable clinical presentation, lack of genotype-phenotype correlation, and low serum phosphate at diagnosis in most cases. These findings emphasize the clinical importance of molecular testing as part of the diagnostic evaluation for cases of non-nutritional rickets.
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Affiliation(s)
| | | | - Erin Cooney
- Department of Pediatrics, University of Texas Medical Branch, Galveston, Texas, USA
| | - Phillip D K Lee
- Department of Pediatrics, University of Texas Medical Branch, Galveston, Texas, USA
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de Brito Chagas J, Cordinhã C, do Carmo C, Alves C, Heath KE, Sousa SB, Gomes C. Vitamin D-Dependent Rickets Type 1A in Two Siblings with a Hypomorphic CYP27B1 Variant Frequent in the African Population. J Pediatr Genet 2024; 13:43-49. [PMID: 38567179 PMCID: PMC10984714 DOI: 10.1055/s-0041-1736559] [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: 04/24/2021] [Accepted: 09/15/2021] [Indexed: 10/20/2022]
Abstract
Vitamin D-dependent type 1A rickets (VDDR-1A) is a rare autosomal recessive disease due to the inability to convert 25-hydroxyvitamin D [25(OH)D] to the active form 1.25-dihydroxyvitamin D [1.25(OH) 2 D] by the enzyme 25(OH)D-1α-hydroxylase leading to low or low-normal serum levels of [1.25(OH) 2 D]. We report two sisters with rickets in whom the diagnosis of VDDR-1A was a challenge. They had normal 1.25(OH)2D levels, which are unusual with this condition but may be explained by the identified genotype. Both have compound heterozygous for two, most likely, hypomorphic CYP27B1 alleles: the novel p.(Arg117Gly) variant, and p.(Ala129Thr), which are present in 0.43% of the African population. This report illustrates the variability of clinical, laboratory, and radiological presentation between two sisters with the same genotype, during phases of faster or slower growth. Genetic testing was crucial for establishing the diagnosis that optimized the management and genetic counseling.
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Affiliation(s)
- Joana de Brito Chagas
- Pediatric Department, Hospital Pediátrico, Centro Hospitalar Universitário de Coimbra (HP-CHUC), Coimbra, Portugal
| | - Carolina Cordinhã
- Pediatric Department, Pediatric Nephrology Unit, Hospital Pediátrico, Centro Hospitalar Universitário de Coimbra (HP-CHUC), Coimbra, Portugal
| | - Carmen do Carmo
- Pediatric Department, Pediatric Nephrology Unit, Hospital Pediátrico, Centro Hospitalar Universitário de Coimbra (HP-CHUC), Coimbra, Portugal
| | - Cristina Alves
- Department of Pediatric Orthopaedics, Hospital Pediátrico, Centro Hospitalar Universitário de Coimbra (HP-CHUC), Coimbra, Portugal
| | - Karen E. Heath
- Institute of Medical and Molecular Genetics, IdiPAZ, Hospital Universitario La Paz, UAM, Madrid, Spain
- Skeletal Dysplasia Multidisciplinary Unit and ERN-BOND, Hospital Universitario La Paz, Madrid, Spain; CIBERER, ISCIII, Madrid, Spain
| | - Sérgio B. Sousa
- Medical Genetics Unit, Skeletal Dysplasia Multidisciplinary Centre and ERN-BOND, Hospital Pediátrico, Centro Hospitalar e Universitário de Coimbra, Coimbra, Portugal
- University Clinic of Genetics, Faculty of Medicine, Universidade de Coimbra, Coimbra, Portugal
| | - Clara Gomes
- Pediatric Department, Pediatric Nephrology Unit, Hospital Pediátrico, Centro Hospitalar Universitário de Coimbra (HP-CHUC), Coimbra, Portugal
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Rohdin C, Wang C, Brander G, Rondahl V, Karlsson Å, Friling L, Fischetti A, Meadows J, Häggström J, Jäderlund KH, Ljungvall I, Lindblad‐Toh K. Mutations in the CYP27B1 gene cause vitamin D dependent rickets in pugs. J Vet Intern Med 2023; 37:1507-1513. [PMID: 37293695 PMCID: PMC10365047 DOI: 10.1111/jvim.16791] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2022] [Accepted: 05/26/2023] [Indexed: 06/10/2023] Open
Abstract
Rickets is a disorder of bone development and can be the result of either dietary or genetic causes. Here, related pugs from 2 litters were included. Three pugs had clinical signs including, lameness, bone deformities, and dyspnea. One other pug was found dead. Radiographs of 2 affected pugs, 5 and 6 months old, showed generalized widening, and irregular margination of the physes of both the appendicular and the axial skeleton with generalized decrease in bone opacity and bulbous swelling of the costochondral junctions. Two pugs had low serum calcium and 1,25 (OH)2 D3 concentrations. Test results further indicated secondary hyperparathyroidism with adequate concentrations of 25-hydroxyvitamin D. Necropsy revealed tongue-like projections of cartilage extending into the metaphysis consistent with rickets, loss of metaphyseal mineralization and lung pathology. Vitamin D-dependent rickets was diagnosed. A truncating mutation in the 1α-hydroxylase gene (CYP27B1) was identified by genome sequence analysis of the pugs with VDDR type 1A. Vitamin D-dependent rickets type 1A can occur in young pugs, and if left untreated is a life-threatening condition. Early medical intervention can reverse clinical signs and should be instituted as soon as possible.
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Affiliation(s)
- Cecilia Rohdin
- Department of Clinical SciencesSwedish University of Agricultural ScienceUppsalaSweden
- Anicura Albano Small Animal HospitalDanderydSweden
| | - Chao Wang
- Department of Medical Biochemistry and MicrobiologyScience for Life LaboratoryUppsalaSweden
| | - Gustaf Brander
- Broad Institute of MIT and HarvardCambridgeMassachusettsUSA
| | | | - Åsa Karlsson
- Department of Medical Biochemistry and MicrobiologyScience for Life LaboratoryUppsalaSweden
| | - Lisa Friling
- AniCura Djursjukhuset Albano Ringgold Standard InstitutionDanderydSweden
| | - Anthony Fischetti
- Department of Diagnostic Imaging, Animal Medical CenterNew YorkNew YorkUSA
| | - Jennifer Meadows
- Department of Medical Biochemistry and MicrobiologyScience for Life LaboratoryUppsalaSweden
| | - Jens Häggström
- Department of Clinical SciencesSwedish University of Agricultural ScienceUppsalaSweden
| | - Karin Hultin Jäderlund
- Department of Companion Animal Clinical SciencesNorges Miljo‐ og Biovitenskapelige Universitet Fakultet for Veterinarmedisin og BiovitenskapOsloNorway
| | - Ingrid Ljungvall
- Department of Clinical SciencesSwedish University of Agricultural ScienceUppsalaSweden
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Al Homyani DK, Alhemaiani SK. Novel Homozygous CYP27B1 Gene Mutation in Vitamin D-Dependent Rickets Type 1A (VDDR1A) Disorder: A Case Report. Front Endocrinol (Lausanne) 2022; 13:862022. [PMID: 35663328 PMCID: PMC9157501 DOI: 10.3389/fendo.2022.862022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Accepted: 03/14/2022] [Indexed: 12/03/2022] Open
Abstract
BACKGROUND Vitamin D-dependent rickets type 1A (VDDR1A) rickets is an uncommon kind of rickets that affects both boys and girls. Children with mutations are normal at birth and present at around 6 months to 2 years of age with symptoms. When suspected, genetic testing is required to confirm the diagnosis. CASE PRESENTATION This is a case report of VDDR1A in a 4-year-old boy who presented with delayed growth, inability to stand, and rachitic bone deformities. The diagnosis was reached by anthropometric measurement, bone profile, and radiological studies, then confirmed by genetic testing, which revealed a homozygous pathogenic variant in the CYP27B1 gene. He was treated with Vitamin-D (alfacalcidol) and oral calcium. CONCLUSION VDDR1A is caused by a mutation in the CYP27B1 gene, which impairs the 1 hydroxylase enzyme, which compromises vitamin-D production.
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Affiliation(s)
- Doua Khalid Al Homyani
- Endocrine Division, Department of Pediatrics, Taif Children Hospital, Taif, Saudi Arabia
- *Correspondence: Doua Khalid Al Homyani, ; Shahad Khalid Alhemaiani,
| | - Shahad Khalid Alhemaiani
- Radiology Division, King Abdulaziz Specialist Hospital, Taif, Saudi Arabia
- *Correspondence: Doua Khalid Al Homyani, ; Shahad Khalid Alhemaiani,
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Kaygusuz SB, Alavanda C, Kirkgoz T, Eltan M, Yavas Abali Z, Helvacioglu D, Guran T, Ata P, Bereket A, Turan S. Does Genotype-Phenotype Correlation Exist in Vitamin D-Dependent Rickets Type IA: Report of 13 New Cases and Review of the Literature. Calcif Tissue Int 2021; 108:576-586. [PMID: 33386952 DOI: 10.1007/s00223-020-00784-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Accepted: 11/28/2020] [Indexed: 11/28/2022]
Abstract
Vitamin D-dependent rickets type IA (VDDR-IA) is caused by biallelic mutations in CYP27B1. Data regarding genotype-phenotype correlation in VDDR-IA are scarce. Here, we aimed to investigate clinical/genotypic features and long-term follow-up of 13 new cases with VDDR-IA and genotype-phenotype correlation of reported cases in the literature. Thirteen patients with VDDR-IA were evaluated. Eight patients had reached their final height at the time of the study and, for whom, long-term outcome data were analyzed. Further, all VDDR-IA patients in the literature (n:183) were analyzed and clinical-genetic features were recorded. The median age of diagnosis was 2.55 ± 1.13 (1.0-12) years. Initial diagnoses before referral to our clinic were nutritional rickets (n:7), hypophosphatemic rickets (n:2), and pseudohypoparathyroidism (n:1). All had biochemical evidence suggestive of VDDR-IA; except one with elevated 1,25(OH)2D3 and another with hyperphosphatemia, in whom pseudohypoparathyroidism was excluded with molecular tests. Combined analyses of our cohort and other series in the literature demonstrated that three most common CYP27B1 mutations are p.F443Pfs*24, c.195 + 2T > G, and p.V88Wfs*71. In Turkish population, p.K192E mutation along with the former two is the most common mutations. Comparison of clinical features demonstrated that c.195 + 2T > G mutation causes the most severe and p.K192E mutation causes the least severe phenotype with respect to age and height at presentation and calcitriol requirement. We found a clear genotype-phenotype correlation in VDDR-IA, notably CYP27B1 intronic c.195 + 2T > G mutation causes a more severe phenotype with lower height SDS at presentation and, higher calcitriol requirement, while less severe phenotype occurs in p.K192E mutation.
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Affiliation(s)
- Sare Betul Kaygusuz
- Department of Pediatric Endocrinology and Diabetes, Marmara University School of Medicine, Istanbul, Turkey
| | - Ceren Alavanda
- Department of Medical Genetics, Marmara University School of Medicine, Istanbul, Turkey
| | - Tarik Kirkgoz
- Department of Pediatric Endocrinology and Diabetes, Marmara University School of Medicine, Istanbul, Turkey
| | - Mehmet Eltan
- Department of Pediatric Endocrinology and Diabetes, Marmara University School of Medicine, Istanbul, Turkey
| | - Zehra Yavas Abali
- Department of Pediatric Endocrinology and Diabetes, Marmara University School of Medicine, Istanbul, Turkey
| | - Didem Helvacioglu
- Department of Pediatric Endocrinology and Diabetes, Marmara University School of Medicine, Istanbul, Turkey
| | - Tulay Guran
- Department of Pediatric Endocrinology and Diabetes, Marmara University School of Medicine, Istanbul, Turkey
| | - Pinar Ata
- Department of Medical Genetics, Marmara University School of Medicine, Istanbul, Turkey
| | - Abdullah Bereket
- Department of Pediatric Endocrinology and Diabetes, Marmara University School of Medicine, Istanbul, Turkey
| | - Serap Turan
- Department of Pediatric Endocrinology and Diabetes, Marmara University School of Medicine, Istanbul, Turkey.
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Zou M, Guven A, BinEssa HA, Al-Rijjal RA, Meyer BF, Alzahrani AS, Shi Y. Molecular Analysis of CYP27B1 Mutations in Vitamin D-Dependent Rickets Type 1A: c.590G > A (p.G197D) Missense Mutation Causes a RNA Splicing Error. Front Genet 2020; 11:607517. [PMID: 33329754 PMCID: PMC7729158 DOI: 10.3389/fgene.2020.607517] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Accepted: 11/10/2020] [Indexed: 11/22/2022] Open
Abstract
Context Vitamin D-dependent rickets type 1A (VDDR1A) is a rare autosomal recessively inherited disorder due to loss-of-function mutations in the CYP27B1 gene. CYP27B1 encodes an enzyme of 25-hydroxyvitamin D-1α-hydroxylase for converting inactive 25-OHD to biologically active 1,25-(OH)2D. Objective To identify underlying genetic defects in patients with VDDR1A. Methods Twelve patients from 7 Turkish and 2 Saudi families were investigated. The coding exons and intron-exon boundaries of the CYP27B1 gene were amplified by Polymerase Chain Reaction (PCR) from peripheral lymphocyte DNA. PCR products were directly sequenced. The consequences of c.590G > A mutation were analyzed by in silico and functional analysis. Results CYP27B1 mutations were identified in all the patients. Two novel mutations were identified in two separate families: c.171delG (family 7) and c.398_400dupAAT (family 8). The intra-exon deletion of c.171delG resulted in a frameshift and premature stop codon 20 amino acids downstream from the mutation (p.L58Cfs∗20). The intra-exon duplication of c.398_400dupAAT generated a premature stop codon at the mutation site (p.W134∗). A missense c.590G > A (p.G197D) mutation was found in a patient from family 4 and caused a defect in pre-mRNA splicing. As a result, two populations of transcripts were detected: the majority of them with intron 3 retention (83%), and the minority (17%) being properly spliced transcripts with about 16% of wild-type enzymatic activity. The remaining nine patients from six families carried a previously reported c.1319_1325dupCCCACCC (F443Pfs∗24) mutation. Clinically, all the patients need continued calcitriol treatment, which was consistent with inactivation of 25-hydroxy vitamin D1α-hydroxylase activity. Conclusion Two novel frameshift CYP27B1 mutations were identified and predicted to inactivate 25-hydroxyvitamin D-1α-hydroxylase. The loss of enzymatic activity by c.590G > A missense mutation was mainly caused by aberrant pre-mRNA splicing.
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Affiliation(s)
- Minjing Zou
- Department of Genetics, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia
| | - Ayla Guven
- Pediatric Endocrinology Clinic, Zeynep Kamil Women and Children Hospital, University of Health Science, Istanbul, Turkey
| | - Huda A BinEssa
- Department of Genetics, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia
| | - Roua A Al-Rijjal
- Department of Genetics, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia
| | - Brian F Meyer
- Pediatric Endocrinology Clinic, Zeynep Kamil Women and Children Hospital, University of Health Science, Istanbul, Turkey
| | - Ali S Alzahrani
- Department of Medicine, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia
| | - Yufei Shi
- Department of Genetics, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia
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Li Y, Yuan X, Chen R, Lin X, Shangguan H, Yang X, Zhang Y. Clinical and genetic analysis of two Chinese families with vitamin D-dependent rickets type IA and follow-up. Orphanet J Rare Dis 2020; 15:273. [PMID: 33004071 PMCID: PMC7528464 DOI: 10.1186/s13023-020-01558-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Accepted: 09/23/2020] [Indexed: 12/02/2022] Open
Abstract
Objective Vitamin D-dependent rickets type IA (VDDR-IA) is a rare autosomal recessive disorder characterized by the early onset of severe rickets. The objectives of this study were twofold: (1) to analyze the clinical characteristics and therapy of two patients with VDDR-IA from two separate Chinese families, and (2) investigate the CYP27B1 gene mutations in two large pedigrees. Methods Medical history, clinical manifestations, physical examination, radiological findings and laboratory data were analyzed from two patients with VDDR-IA. Serum 1, 25-dihydroxyvitamin D [1, 25-(OH)2D3] of the two patients and their respective families were measured by ELISA and blood samples from both families was obtained for CYP27B1 gene sequence. Results Two patients had typical manifestations and radiological evidence of rickets. Laboratory data showed hypocalcaemia and hypophosphataemia, along with high levels of serum alkaline phosphatase, parathyroid hormone and 25-hydroxyvitamin D3. However, serum 1,25-(OH)2D3 level were low in the patients but normal in their family members. Genetic sequence identified two patients were homozygous for a duplication mutation in exon 8 of CYP27B1 gene (c.1319_1325dupCCCACCC, p.Phe443Profs * 24). After treating with calcitriol and calcium, there was biochemical improvement with normalization of serum calcium and phosphorus, and radiographic evidence of compensatory skeletal mineralization. One patient developed nephrocalcinosis during follow-up. Conclusions This study identified a recurrent seven-nucleotide insertion of CYP27B1 in two large pedigrees, and compared the clinical characteristics and individual therapy of two affected patients. Additionally, our experience further supports the notion that nephrocalcinosis can occur even on standard doses of calcitriol and oral calcium, and normal level of serum calcium, phosphorus, PTH and 25-(OH)D3.
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Affiliation(s)
- Yunfei Li
- Department of Endocrinology, Genetics and Metabolism, Fuzhou Children's Hospital of Fujian Medical University, No. 145, 817 Middle Road, Fuzhou, 350005, China.,Affiliated Dongfeng General Hospital of Hubei Medical College, Shiyan, 442008, China
| | - Xin Yuan
- Department of Endocrinology, Genetics and Metabolism, Fuzhou Children's Hospital of Fujian Medical University, No. 145, 817 Middle Road, Fuzhou, 350005, China
| | - Ruimin Chen
- Department of Endocrinology, Genetics and Metabolism, Fuzhou Children's Hospital of Fujian Medical University, No. 145, 817 Middle Road, Fuzhou, 350005, China.
| | - Xiangquan Lin
- Department of Endocrinology, Genetics and Metabolism, Fuzhou Children's Hospital of Fujian Medical University, No. 145, 817 Middle Road, Fuzhou, 350005, China
| | - Huakun Shangguan
- Department of Endocrinology, Genetics and Metabolism, Fuzhou Children's Hospital of Fujian Medical University, No. 145, 817 Middle Road, Fuzhou, 350005, China
| | - Xiaohong Yang
- Department of Endocrinology, Genetics and Metabolism, Fuzhou Children's Hospital of Fujian Medical University, No. 145, 817 Middle Road, Fuzhou, 350005, China
| | - Ying Zhang
- Department of Endocrinology, Genetics and Metabolism, Fuzhou Children's Hospital of Fujian Medical University, No. 145, 817 Middle Road, Fuzhou, 350005, China
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Sen A, Stark H. Role of cytochrome P450 polymorphisms and functions in development of ulcerative colitis. World J Gastroenterol 2019; 25:2846-2862. [PMID: 31249444 PMCID: PMC6589734 DOI: 10.3748/wjg.v25.i23.2846] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Revised: 04/26/2019] [Accepted: 05/08/2019] [Indexed: 02/06/2023] Open
Abstract
Cytochromes P450s (CYPs) are terminal enzymes in CYP dependent monooxygenases, which constitute a superfamily of enzymes catalysing the metabolism of both endogenous and exogenous substances. One of their main tasks is to facilitate the excretion of these substances and eliminate their toxicities in most phase 1 reactions. Endogenous substrates of CYPs include steroids, bile acids, eicosanoids, cholesterol, vitamin D and neurotransmitters. About 80% of currently used drugs and environmental chemicals comprise exogenous substrates for CYPs. Genetic polymorphisms of CYPs may affect the enzyme functions and have been reported to be associated with various diseases and adverse drug reactions among different populations. In this review, we discuss the role of some critical CYP isoforms (CYP1A1, CYP2D6, CYP2J2, CYP2R1, CYP3A5, CYP3A7, CYP4F3, CYP24A1, CYP26B1 and CYP27B1) in the pathogenesis or aetiology of ulcerative colitis concerning gene polymorphisms. In addition, their significance in metabolism concerning ulcerative colitis in patients is also discussed showing a clear underestimation in genetic studies performed so far.
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Affiliation(s)
- Alaattin Sen
- Department of Molecular Biology and Genetics, Faculty of Life and Natural Sciences, Abdullah Gul University, Kayseri 38080, Turkey
- Biology Department, Faculty of Arts and Sciences, Pamukkale University, Denizli 20070, Turkey
| | - Holger Stark
- Institute of Pharmaceutical and Medicinal Chemistry, Heinrich Heine University Düsseldorf, Duesseldorf 40225, Germany
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Kim YM, Jang YY, Jeong JE, Park HJ, Jang JH, Kim JK. A case of vitamin D hydroxylation-deficient rickets type 1A caused by 2 novel pathogenic variants in CYP27B1 gene. Ann Pediatr Endocrinol Metab 2019; 24:137-141. [PMID: 31261480 PMCID: PMC6603605 DOI: 10.6065/apem.2019.24.2.137] [Citation(s) in RCA: 5] [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: 01/27/2019] [Accepted: 03/11/2019] [Indexed: 11/20/2022] Open
Abstract
Vitamin D hydroxylation-deficient rickets type 1A (VDDR1A, OMIM 264700) is a rare autosomal recessive inherited disorder. Pathogenic variants in the CYP27B1 gene lead to loss of 1α-hydroxylase activity. We report the case of a 22-month-old toddler who presented with growth retardation and delayed development. The patient exhibited the typical laboratory findings of VDDR1A, including hypocalcemia (calcium: 5.2 mg/dL), elevated serum level of alkaline phosphatase (2,600 U/L), elevated serum level of intact-parathyroid hormone (238 pg/mL), low 1,25(OH)2D3 level (11.2 pg/mL), and normal 25(OH)D3 level (40.7 ng/mL). His height and weight were 76.5 cm and 9.5 kg, respectively (both <3rd percentile). The Bayley Scales of Infant and Toddler Development II indicated significantly delayed development (mental development index <50, psychomotor development index <50). The patient was a compound heterozygous for two novel pathogenic variants in the CYP27B1 gene: c.57_69del (p.Glu20Profs*2) and c.171dupG (p.Leu58Alafs*275), inherited from his mother and father, respectively. The patient showed remarkable improvement after treatment with calcitriol and calcium carbonate.
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Affiliation(s)
- You-Min Kim
- Department of Pediatrics, Catholic University of Daegu School of Medicine, Daegu, Korea
| | - Yoon-Young Jang
- Department of Pediatrics, Catholic University of Daegu School of Medicine, Daegu, Korea
| | - Ji-Eun Jeong
- Department of Pediatrics, Catholic University of Daegu School of Medicine, Daegu, Korea
| | - Hye-Jin Park
- Department of Pediatrics, Catholic University of Daegu School of Medicine, Daegu, Korea
| | | | - Jin-Kyung Kim
- Department of Pediatrics, Catholic University of Daegu School of Medicine, Daegu, Korea,Address for correspondence: Jin-Kyung Kim, MD, PhD Department of Pediatrics, Catholic University of Daegu School of Medicine, 33 Duryugongwon-ro 17- gil, Nam-gu, Daegu 42472, Korea Tel: +82-53-650-4240 Fax: +82-53-621-4106 E-mail:
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Dursun F, Özgürhan G, Kırmızıbekmez H, Keskin E, Hacıhamdioğlu B. Genetic and Clinical Characteristics of Patients with Vitamin D Dependent Rickets Type 1A. J Clin Res Pediatr Endocrinol 2019; 11:34-40. [PMID: 30282619 PMCID: PMC6398191 DOI: 10.4274/jcrpe.galenos.2018.2018.0121] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
OBJECTIVE Vitamin D dependent rickets type 1A (VDDR1A) is an autosomal recessive disorder caused by mutations in the 1α-hydroxylase gene (CYB27B1). As it may be confused with nutritional rickets and hypophosphatemic rickets, genetic analysis is important for making a correct diagnosis. METHODS We analysed genomic DNA from 11 patients from eight different Turkish families. The patients were recruited for our studies if they presented with a diagnosis of VDDR. RESULTS The mean ± standard deviation age at diagnosis was 13.1±7.4 months. Seven patients had mild hypocalcemia at presentation while four patients had normal calcium concentrations. All patients underwent CYP27B1 gene analysis. The most prevalent mutation was the c.195 + 2T>G splice donor site mutation, affecting five out of 11 patients with VDDR1A. Two patients from the fourth family were compound heterozygous for c.195 + 2T>G and c.195 + 2 T>A in intron-1. Two patients, from different families, were homozygous for a previously reported duplication mutation in exon 8 (1319_1325dupCCCACCC, Phe443Profs*24). One patient had a homozygous splice site mutation in intron 7 (c.1215 + 2 T>A) and one patient had a homozygous mutation in exon 9 (c.1474 C>T). CONCLUSION Intron-1 mutation was the most common mutation, as previously reported. All patients carrying that mutation were from same city of origin suggesting a “founder” or a “common ancestor” effect. VDDR1A should definitely be considered when a patient with signs of rickets has a normal 25-OHD level or when there is unresponsiveness to vitamin D treatment.
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Affiliation(s)
- Fatma Dursun
- Ümraniye Training and Research Hospital, Clinic of Pediatric Endocrinology, İstanbul, Turkey,* Address for Correspondence: Ümraniye Training and Research Hospital, Clinic of Pediatric Endocrinology, İstanbul, Turkey Phone: +90 505 267 14 03 E-mail:
| | - Gamze Özgürhan
- Süleymaniye Maternity and Children’s Training and Research Hospital, Clinic of Paediatrics, İstanbul, Turkey
| | - Heves Kırmızıbekmez
- Ümraniye Training and Research Hospital, Clinic of Pediatric Endocrinology, İstanbul, Turkey
| | - Ece Keskin
- Süleymaniye Maternity and Children’s Training and Research Hospital, Clinic of Medical Genetic, İstanbul, Turkey
| | - Bülent Hacıhamdioğlu
- İstinye University Faculty of Medicine, Department of Pediatric Endocrinology, İstanbul, Turkey
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Chi Y, Sun J, Pang L, Jiajue R, Jiang Y, Wang O, Li M, Xing X, Hu Y, Zhou X, Meng X, Xia W. Mutation update and long-term outcome after treatment with active vitamin D 3 in Chinese patients with pseudovitamin D-deficiency rickets (PDDR). Osteoporos Int 2019; 30:481-489. [PMID: 30382318 DOI: 10.1007/s00198-018-4607-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/09/2017] [Accepted: 06/15/2018] [Indexed: 01/08/2023]
Abstract
UNLABELLED Pseudovitamin D-deficiency rickets is a rare disease which is caused by CYP27B1. In this study, we identified 9 mutations in 7 PDDR patients. In addition, we observed the response to long-term treatment of calcitriol in 15 Chinese patients with PDDR, which showed that the biochemical abnormalities had been corrected satisfactorily after 1-year treatment. INTRODUCTION Pseudovitamin D-deficiency rickets is a rare autosomal recessive disorder resulting from a defect in 25-hydroxyvitamin D 1α-hydroxylase, which is encoded by CYP27B1. The purpose of this study was to identify the CYP27B1 mutations and investigate the response to long-term treatment of calcitriol in Chinese patients with PDDR. METHODS We investigated CYP27B1 mutations in seven individuals from six separate families. To investigate the response to long-term (13 years) treatment with calcitriol in PDDR patients, we additionally collected clinical data of eight families from our previous report and analyzed their biochemical parameter and radiographic changes during the treatment. RESULTS Nine different mutations were identified: two novel missense mutations (G194R, R259L), three novel and one reported deletion mutations (c1442delA, c1504delA, c311-321del, and c. 48-60del), two novel nonsense mutations (c.85G>T, c.580G>T), and a reported insertion mutation (c1325-1332insCCCACCC). The statistical analysis revealed that parathyroid hormone (PTH) and ALP significantly decreased after 6-month and 1-year treatment with calcitriol respectively. Urine calcium was measured in all the patients without kidney stones being documented. After 6-year treatment, the radiographic abnormalities had also been improved. Two patients who had reached their final height are both with short stature (height Z-score below - 2.0). CONCLUSIONS We identified seven novel mutations of CYP27B1 gene in seven Chinese PDDR families. Our findings revealed after 1-year treatment of active vitamin D3, PTH and ALP significantly decreased. The correction of the biochemical abnormalities had not improved the final height satisfactorily.
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Affiliation(s)
- Y Chi
- Department of Endocrinology, Key Laboratory of Endocrinology, Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Shuaifuyuan No. 1, Wangfujing, Dongcheng District, Beijing, 100730, China
| | - J Sun
- Department of Endocrinology, Key Laboratory of Endocrinology, Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Shuaifuyuan No. 1, Wangfujing, Dongcheng District, Beijing, 100730, China
| | - L Pang
- Department of Endocrinology, Key Laboratory of Endocrinology, Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Shuaifuyuan No. 1, Wangfujing, Dongcheng District, Beijing, 100730, China
| | - R Jiajue
- Department of Endocrinology, Key Laboratory of Endocrinology, Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Shuaifuyuan No. 1, Wangfujing, Dongcheng District, Beijing, 100730, China
| | - Y Jiang
- Department of Endocrinology, Key Laboratory of Endocrinology, Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Shuaifuyuan No. 1, Wangfujing, Dongcheng District, Beijing, 100730, China
| | - O Wang
- Department of Endocrinology, Key Laboratory of Endocrinology, Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Shuaifuyuan No. 1, Wangfujing, Dongcheng District, Beijing, 100730, China
| | - M Li
- Department of Endocrinology, Key Laboratory of Endocrinology, Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Shuaifuyuan No. 1, Wangfujing, Dongcheng District, Beijing, 100730, China
| | - X Xing
- Department of Endocrinology, Key Laboratory of Endocrinology, Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Shuaifuyuan No. 1, Wangfujing, Dongcheng District, Beijing, 100730, China
| | - Y Hu
- Department of Endocrinology, Key Laboratory of Endocrinology, Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Shuaifuyuan No. 1, Wangfujing, Dongcheng District, Beijing, 100730, China
| | - X Zhou
- Department of Endocrinology, Key Laboratory of Endocrinology, Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Shuaifuyuan No. 1, Wangfujing, Dongcheng District, Beijing, 100730, China
| | - X Meng
- Department of Endocrinology, Key Laboratory of Endocrinology, Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Shuaifuyuan No. 1, Wangfujing, Dongcheng District, Beijing, 100730, China
| | - W Xia
- Department of Endocrinology, Key Laboratory of Endocrinology, Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Shuaifuyuan No. 1, Wangfujing, Dongcheng District, Beijing, 100730, China.
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Ahmad N, Mohamed Sobaihi M, Al-Jabri M, Al –Esaei NA, Al Zaydi AM. Acute respiratory failure and generalized hypotonia secondary to vitamin D dependent rickets type 1A. Int J Pediatr Adolesc Med 2018; 5:78-81. [PMID: 30805538 PMCID: PMC6363249 DOI: 10.1016/j.ijpam.2018.05.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2018] [Revised: 05/06/2018] [Accepted: 05/13/2018] [Indexed: 06/09/2023]
Abstract
Vitamin D dependent rickets is a rare autosomal recessive disorder secondary to mutation in 1 α hydroxylase enzyme gene. We are presenting a case of a two-year-old boy with vitamin D dependent rickets type 1A whose diagnosis was missed for a long period and he was treated as nutritional rickets. He suffered with severe hypotonia and regressing milestones. Severe hypotonia with proximal muscle weakness caused respiratory failure which required intensive care admission and mechanical ventilation. DNA analysis revealed previously reported homozygous mutation in CYP27B1 gene (p.Arg429Pro (R429P) at exon c.1286 G > C). Rare genetic disorders of rickets are not considered in early course of disease in regions with high prevalence of vitamin D deficiency. This severe presentation of rickets highlights the need of close monitoring of treatment response and consideration of other differential diagnosis in children who are not responding to vitamin D supplements. There is a high prevalence of genetic disorders particularly autosomal recessive conditions in societies having high rate of inter-family and consanguineous marriages.
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Affiliation(s)
- Noman Ahmad
- Corresponding author. Department of Pediatrics, King Faisal Specialist Hospital and Research Centre Prince Saud Al-Faisal Road, P O Box 40047, Jeddah, 21499; Saudi Arabia
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13
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Abstract
Rickets is a metabolic bone disease that develops as a result of inadequate mineralization of growing bone due to disruption of calcium, phosphorus and/or vitamin D metabolism. Nutritional rickets remains a significant child health problem in developing countries. In addition, several rare genetic causes of rickets have also been described, which can be divided into two groups. The first group consists of genetic disorders of vitamin D biosynthesis and action, such as vitamin D-dependent rickets type 1A (VDDR1A), vitamin D-dependent rickets type 1B (VDDR1B), vitamin D-dependent rickets type 2A (VDDR2A), and vitamin D-dependent rickets type 2B (VDDR2B). The second group involves genetic disorders of excessive renal phosphate loss (hereditary hypophosphatemic rickets) due to impairment in renal tubular phosphate reabsorption as a result of FGF23-related or FGF23-independent causes. In this review, we focus on clinical, laboratory and genetic characteristics of various types of hereditary rickets as well as differential diagnosis and treatment approaches.
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Affiliation(s)
- Sezer Acar
- Dokuz Eylül University Faculty of Medicine, Department of Pediatric Endocrinology, İzmir, Turkey
| | - Korcan Demir
- Dokuz Eylül University Faculty of Medicine, Department of Pediatric Endocrinology, İzmir, Turkey
| | - Yufei Shi
- King Faisal Specialist Hospital & Research Centre, Department of Genetics, Riyadh, Saudi Arabia
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14
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Abstract
Rickets is a bone disease associated with abnormal serum calcium and phosphate levels. The clinical presentation is heterogeneous and depends on the age of onset and pathogenesis but includes bowing deformities of the legs, short stature and widening of joints. The disorder can be caused by nutritional deficiencies or genetic defects. Mutations in genes encoding proteins involved in vitamin D metabolism or action, fibroblast growth factor 23 (FGF23) production or degradation, renal phosphate handling or bone mineralization have been identified. The prevalence of nutritional rickets has substantially declined compared with the prevalence 200 years ago, but the condition has been re-emerging even in some well-resourced countries; prematurely born infants or breastfed infants who have dark skin types are particularly at risk. Diagnosis is usually established by medical history, physical examination, biochemical tests and radiography. Prevention is possible only for nutritional rickets and includes supplementation or food fortification with calcium and vitamin D either alone or in combination with sunlight exposure. Treatment of typical nutritional rickets includes calcium and/or vitamin D supplementation, although instances infrequently occur in which phosphate repletion may be necessary. Management of heritable types of rickets associated with defects in vitamin D metabolism or activation involves the administration of vitamin D metabolites. Oral phosphate supplementation is usually indicated for FGF23-independent phosphopenic rickets, whereas the conventional treatment of FGF23-dependent types of rickets includes a combination of phosphate and activated vitamin D; an anti-FGF23 antibody has shown promising results and is under further study.
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15
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Miller WL. Genetic disorders of Vitamin D biosynthesis and degradation. J Steroid Biochem Mol Biol 2017; 165:101-108. [PMID: 27060335 DOI: 10.1016/j.jsbmb.2016.04.001] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Revised: 04/03/2016] [Accepted: 04/05/2016] [Indexed: 01/10/2023]
Abstract
Vitamin D, an inactive secosteroid pro-hormone, is produced by the action of ultraviolet light on 7-dehydrocholesterol in the skin. The active hormone, 1,25(OH)2D is produced by sequential 25-hydroxylation in the liver, principally by CYP2R1, and 1α-hydroxylation in the kidney by CYP27B1. Mutations in CYP27B1 cause 1α-hydroxylase deficiency, also known as vitamin D dependent rickets type I or hereditary pseudo-vitamin D deficient rickets; very rare mutations in CYP2R1 can cause 25-hydroxylase deficiency. Both deficiencies cause hypocalcemia, secondary hyperparathyroidism, severe rickets in infancy, and low serum concentrations of 1,25(OH)2D; both disorders respond to hormonal replacement therapy with calcitriol. The inactivation of vitamin D is principally initiated by its 23- and 24-hydroxylation by CYP24A1. Mutations in CYP24A1 can cause both severe neonatal hypercalcemia and a less severe adult hypercalcemic syndrome. Other pathways of vitamin D metabolism are under investigation, notably its 20-hydroxylation by the cholesterol side-chain cleavage enzyme, CYP11A1.
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Affiliation(s)
- Walter L Miller
- Center for Reproductive Sciences and Department of Pediatrics, HSE 1634, University of California San Francisco, San Francisco, CA 94143-0556, USA.
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16
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Özcabı B, Tahmiscioğlu Bucak F, Jaferova S, Oruç Ç, Adrovic A, Ceylaner S, Ercan O, Evliyaoğlu O. A Case of Vitamin D-Dependent Rickets Type 1A with a Novel Mutation in the Uzbek Population. J Clin Res Pediatr Endocrinol 2016; 8:484-489. [PMID: 27353739 PMCID: PMC5198011 DOI: 10.4274/jcrpe.3128] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
Vitamin D-dependent rickets type 1A (VDDR-1A) (Online Mendelian Inheritance in Man #264700) is a rare, autosomal recessively inherited disorder due to inactivating mutations in CYP27B1. It is characterized by early onset of rickets with hypocalcemia. We aimed to describe the clinical and laboratory findings in a VDDR-1A case and to report a novel homozygote truncating mutation NM_000785.3 c.403C>T (p.Q135*) in CYP27B1 which to our knowledge is the first described mutation in the Uzbek population. The patient was admitted with tetany at the age of 12 months. He was a healthy Uzbek boy until 9 months of age when he had a seizure due to hypocalcemia. Vitamin D treatment was given orally in Turkmenistan (no data available for dose and duration). The patient was the product of a consanguineous marriage. His brother had died with hypocalcemia and pneumonia. At physical examination, anthropometric measurements were within normal limits; he had caput quadratum, enlarged wrists, and carpopedal spasm. Blood calcium, phosphorus, alkaline phosphatase, and parathormone (PTH) levels were 5.9 mg/dL, 3.5 mg/dL, 987 IU/L, and 182.8 pg/mL (12-72), respectively. Radiological findings included cupping and fraying of the radial and ulnar metaphyses. Renal ultrasound revealed nephrocalcinosis (grade 1). Despite high serum PTH and 25-hydroxyvitamin D3 levels, 1,25-dihydroxyvitamin D3 level was low, suggesting a diagnosis of VDDR-1A. The patient was treated with calcium carbonate and calcitriol. DNA sequencing revealed a novel homozygous mutation of NM_000785.3 c.403C>T (p.Q135*) in CYP27B1. VDDR-1A is a rare disorder which needs to be considered even in countries where nutritional vitamin D deficiency is still common.
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Affiliation(s)
- Bahar Özcabı
- İstanbul University Cerrahpaşa Faculty of Medicine, Department of Pediatric Endocrinology, İstanbul, Turkey
| | - Feride Tahmiscioğlu Bucak
- İstanbul University Cerrahpaşa Faculty of Medicine, Department of Pediatric Endocrinology, İstanbul, Turkey
| | - Sevinç Jaferova
- İstanbul University Cerrahpaşa Faculty of Medicine, Department of Pediatric Endocrinology, İstanbul, Turkey
| | - Çiğdem Oruç
- İstanbul University Cerrahpaşa Faculty of Medicine, Department of Pediatric Endocrinology, İstanbul, Turkey
| | - Amra Adrovic
- İstanbul University Cerrahpaşa Faculty of Medicine, Department of Pediatric Endocrinology, İstanbul, Turkey
| | - Serdar Ceylaner
- Intergen Genetic Center and Yüksek İhtisas University Faculty of Medicine, Department of Medical Genetics, Ankara, Turkey
| | - Oya Ercan
- İstanbul University Cerrahpaşa Faculty of Medicine, Department of Pediatric Endocrinology, İstanbul, Turkey
| | - Olcay Evliyaoğlu
- İstanbul University Cerrahpaşa Faculty of Medicine, Department of Pediatric Endocrinology, İstanbul, Turkey, E-mail:
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17
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Zalewski A, Ma NS, Legeza B, Renthal N, Flück CE, Pandey AV. Vitamin D-Dependent Rickets Type 1 Caused by Mutations in CYP27B1 Affecting Protein Interactions With Adrenodoxin. J Clin Endocrinol Metab 2016; 101:3409-18. [PMID: 27399352 DOI: 10.1210/jc.2016-2124] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
CONTEXT CYP27B1 converts 25-hydroxyvitamin D3 to active 1,25-dihydroxyvitamin D3, playing a vital role in calcium homeostasis and bone growth. Vitamin D-dependent rickets type 1 (VDDR-1) is a rare autosomal recessive disorder caused by mutations in CYP27B1. OBJECTIVE The objective of the study was an enzymatic and structural analysis of mutations in a patient with calcipenic rickets. Design, Setting, Patient, and Intervention: Two siblings presented with calcipenic rickets and normal 1,25-dihydroxyvitamin D3 levels. CYP27B1 gene analysis showed compound heterozygous mutations confirming VDDR-1. We studied wild-type CYP27B1 and mutations H441Y and R459L by computational homology modeling, molecular dynamics simulations, and functional studies using a luciferase assay. The patients were successfully treated with calcitriol. MAIN OUTCOME The main outcomes of the study were novel mutations leading to a severe loss of CYP27B1 activities for metabolism of 25-hydroxyvitamin D3. RESULTS Mitochondrial cytochrome P450s require adrenodoxin (FDX1) and adrenodoxin reductase. We created models of CYP27B1-FDX1 complex, which revealed negative effects of mutations H441Y and R459L. Upon structural analysis, near-identical folds, protein contact areas, and orientations of heme/iron-sulfur cluster suggested that both mutations may destabilize the CYP27B1-FDX1 complex by negating directional interactions with adrenodoxin. This system is highly sensitive to small local changes modulating the binding/dissociation of adrenodoxin, and electron-transporting efficiency might change with mutations at the surface. Functional assays confirmed this hypothesis and showed severe loss of activity of CYP27B1 by both mutations. CONCLUSIONS This is the first report of mutations in CYP27B1 causing VDDR-1 by affecting protein-protein interactions with FDX1 that results in reduced CYP27B1 activities. Detailed characterization of mutations in CYP27B1 is required for understanding the novel molecular mechanisms causing VDDR-1.
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Affiliation(s)
- Adam Zalewski
- Division of Pediatric Endocrinology, Diabetology, and Metabolism (A.Z., B.L., C.E.F., A.V.P.), Department of Pediatrics, University Children's Hospital, Inselspital, Bern, and Department of Clinical Research, University of Bern, CH-3010 Bern, Switzerland; and Division of Endocrinology (N.S.M., N.R.), Boston Children's Hospital, and Department of Pediatrics, Harvard Medical School, Boston, Massachusetts 02114
| | - Nina S Ma
- Division of Pediatric Endocrinology, Diabetology, and Metabolism (A.Z., B.L., C.E.F., A.V.P.), Department of Pediatrics, University Children's Hospital, Inselspital, Bern, and Department of Clinical Research, University of Bern, CH-3010 Bern, Switzerland; and Division of Endocrinology (N.S.M., N.R.), Boston Children's Hospital, and Department of Pediatrics, Harvard Medical School, Boston, Massachusetts 02114
| | - Balazs Legeza
- Division of Pediatric Endocrinology, Diabetology, and Metabolism (A.Z., B.L., C.E.F., A.V.P.), Department of Pediatrics, University Children's Hospital, Inselspital, Bern, and Department of Clinical Research, University of Bern, CH-3010 Bern, Switzerland; and Division of Endocrinology (N.S.M., N.R.), Boston Children's Hospital, and Department of Pediatrics, Harvard Medical School, Boston, Massachusetts 02114
| | - Nora Renthal
- Division of Pediatric Endocrinology, Diabetology, and Metabolism (A.Z., B.L., C.E.F., A.V.P.), Department of Pediatrics, University Children's Hospital, Inselspital, Bern, and Department of Clinical Research, University of Bern, CH-3010 Bern, Switzerland; and Division of Endocrinology (N.S.M., N.R.), Boston Children's Hospital, and Department of Pediatrics, Harvard Medical School, Boston, Massachusetts 02114
| | - Christa E Flück
- Division of Pediatric Endocrinology, Diabetology, and Metabolism (A.Z., B.L., C.E.F., A.V.P.), Department of Pediatrics, University Children's Hospital, Inselspital, Bern, and Department of Clinical Research, University of Bern, CH-3010 Bern, Switzerland; and Division of Endocrinology (N.S.M., N.R.), Boston Children's Hospital, and Department of Pediatrics, Harvard Medical School, Boston, Massachusetts 02114
| | - Amit V Pandey
- Division of Pediatric Endocrinology, Diabetology, and Metabolism (A.Z., B.L., C.E.F., A.V.P.), Department of Pediatrics, University Children's Hospital, Inselspital, Bern, and Department of Clinical Research, University of Bern, CH-3010 Bern, Switzerland; and Division of Endocrinology (N.S.M., N.R.), Boston Children's Hospital, and Department of Pediatrics, Harvard Medical School, Boston, Massachusetts 02114
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18
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Demir K, Kattan WE, Zou M, Durmaz E, BinEssa H, Nalbantoğlu Ö, Al-Rijjal RA, Meyer B, Özkan B, Shi Y. Novel CYP27B1 Gene Mutations in Patients with Vitamin D-Dependent Rickets Type 1A. PLoS One 2015; 10:e0131376. [PMID: 26132292 PMCID: PMC4489500 DOI: 10.1371/journal.pone.0131376] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Accepted: 05/31/2015] [Indexed: 12/30/2022] Open
Abstract
The CYP27B1 gene encodes 25-hydroxyvitamin D-1α-hydroxylase. Mutations of this gene cause vitamin D-dependent rickets type 1A (VDDR-IA, OMIM 264700), which is a rare autosomal recessive disorder. To investigate CYP27B1 mutations, we studied 8 patients from 7 unrelated families. All coding exons and intron-exon boundaries of CYP27B1 gene were amplified by PCR from peripheral leukocyte DNA and subsequently sequenced. Homozygous mutations in the CYP27B1 gene were found in all the patients and heterozygous mutations were present in their normal parents. One novel single nucleotide variation (SNV, c.1215 T>C, p.R379R in the last nucleotide of exon 7) and three novel mutations were identified:, a splice donor site mutation (c.1215+2T>A) in intron 7, a 16-bp deletion in exon 6 (c.1022-1037del16), and a 2-bp deletion in exon 5 (c.934_935delAC). Both c.1215 T>C and c.1215+2T>A were present together in homozygous form in two unrelated patients, and caused exon 7 skipping. However, c.1215 T>C alone has no effect on pre-mRNA splicing. The skipping of exon 7 resulted in a shift of downstream reading frame and a premature stop codon 57 amino acids from L380 (p.L380Afs*57). The intra-exon deletions of c.1022-1037del16 and c.934_935delAC also resulted in a frameshift and the creation of premature stop codons at p.T341Rfs*5, and p.T312Rfs*19, respectively, leading to the functional inactivation of the CYP27B1 gene. Clinically, all the patients required continued calcitriol treatment and the clinical presentations were consistent with the complete loss of vitamin D1α-hydroxylase activity. In conclusion, three novel mutations have been identified. All of them caused frameshift and truncated proteins. The silent c.1215 T>C SNV has no effect on pre-mRNA splicing and it is likely a novel SNP. The current study further expands the CYP27B1 mutation spectrum.
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Affiliation(s)
- Korcan Demir
- Division of Pediatric Endocrinology, Dr. Behçet Uz Children's Hospital, İzmir, Turkey
| | - Walaa E Kattan
- College of Science and General Studies, Alfaisal University, Riyadh, Saudi Arabia; 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
| | - Erdem Durmaz
- Department of Pediatric Endocrinology, Sifa University, Bornova Health Application and Research Center, İzmir, Turkey
| | - Huda BinEssa
- Department of Genetics, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia
| | - Özlem Nalbantoğlu
- Division of Pediatric Endocrinology, Dr. Behçet Uz Children's Hospital, İzmir, Turkey
| | - Roua A Al-Rijjal
- Department of Genetics, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia
| | - Brian Meyer
- Department of Genetics, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia
| | - Behzat Özkan
- Division of Pediatric Endocrinology, Dr. Behçet Uz Children's Hospital, İzmir, Turkey
| | - Yufei Shi
- Department of Genetics, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia
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19
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Niino M, Miyazaki Y. Genetic polymorphisms related to vitamin D and the therapeutic potential of vitamin D in multiple sclerosis. Can J Physiol Pharmacol 2015; 93:319-25. [DOI: 10.1139/cjpp-2014-0374] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Vitamin D receptors (VDRs), which are responsible for most vitamin D functions, are expressed on various immune cells. Vitamin D is considered to be a potent immunomodulator. A variety of cells in the central nervous system (CNS) also express VDRs; thus, vitamin D may play a role in the regulation of neurodegeneration and repair processes within the CNS. Considered together with epidemiological studies, low vitamin D status is reckoned to be one of the risk factors for multiple sclerosis (MS). Further, vitamin D is considered to be a possible treatment for MS. However, previous clinical trials with small cohorts have not demonstrated significant effects of vitamin D in MS. Current ongoing clinical trials with large cohorts could provide answers with respect to the clinical effects of vitamin D in MS. However, genetic studies have suggested that genes associated with vitamin D, including VDRs, are susceptible genes for MS. Vitamin D needs to be considered from the perspective of the interaction between vitamin-D-related genetic factors and environmental factors affecting vitamin D levels.
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Affiliation(s)
- Masaaki Niino
- Department of Clinical Research, Hokkaido Medical Center, Sapporo, Japan
| | - Yusei Miyazaki
- Department of Clinical Research, Hokkaido Medical Center, Sapporo, Japan
- Department of Neurology, Hokkaido Medical Center, Sapporo, Japan
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20
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Ito N, Peña AS, Perano S, Atkins GJ, Findlay DM, Couper JJ. First Australian report of vitamin D-dependent rickets type I. Med J Aust 2014; 201:420-1. [PMID: 25296067 DOI: 10.5694/mja13.00220] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2013] [Accepted: 05/21/2014] [Indexed: 11/17/2022]
Affiliation(s)
- Nobuaki Ito
- Centre for Orthopaedic and Trauma Research, University of Adelaide, Adelaide, SA, Australia.
| | - Alexia S Peña
- Discipline of Paediatrics, University of Adelaide and Robinson Research Institute, Adelaide, SA, Australia
| | - Shiree Perano
- Endocrinology and Diabetes Centre, Women's and Children's Hospital, Adelaide, SA, Australia
| | - Gerald J Atkins
- Centre for Orthopaedic and Trauma Research, University of Adelaide, Adelaide, SA, Australia
| | - David M Findlay
- Centre for Orthopaedic and Trauma Research, University of Adelaide, Adelaide, SA, Australia
| | - Jennifer J Couper
- Discipline of Paediatrics, University of Adelaide and Robinson Research Institute, Adelaide, SA, Australia
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Fechter K, Porollo A. MutaCYP: Classification of missense mutations in human cytochromes P450. BMC Med Genomics 2014; 7:47. [PMID: 25073475 PMCID: PMC4119178 DOI: 10.1186/1755-8794-7-47] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2014] [Accepted: 07/24/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Cytochrome P450 monooxygenases (CYPs) represent a large and diverse family of enzymes involved in various biological processes in humans. Individual genome sequencing has revealed multiple mutations in human CYPs, and many missense mutations have been associated with variety of diseases. Since 3D structures are not resolved for most human CYPs, there is a need for a reliable sequence-based prediction that discriminates benign and disease causing mutations. METHODS A new prediction method (MutaCYP) has been developed for scoring de novo missense mutations to have a deleterious effect. The method utilizes only five features, all of which are sequence-based: predicted relative solvent accessibility (RSA), variance of predicted RSA among the residues in close sequence proximity, Z-score of Shannon entropy for a given position, difference in similarity scores and weighted difference in size between wild type and new amino acids. The method is based on a single neural network. RESULTS MutaCYP achieves MCC = 0.70, Q2 = 88.52%, Recall = 93.40% with Precision = 91.09%, and AUC = 0.909. Comparative evaluation with other existing methods indicates that MutaCYP outperforms SIFT and PolyPhen-2. Predictions by MutaCYP appear to be orthogonal to predictions by the evaluated methods. Potential issues on reliability of annotations of mutations in the existing databases are discussed. CONCLUSIONS A new accurate method, MutaCYP, for classification of missense mutations in human CYPs is presented. The prediction model consists of only five sequence-based features, including a real-valued predicted relative solvent accessibility. The method is publicly available at http://research.cchmc.org/MutaSense/.
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Affiliation(s)
| | - Aleksey Porollo
- Department of Environmental Health, University of Cincinnati, Cincinnati, OH, USA.
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Niino M, Miyazaki Y, Fukazawa T, Kikuchi S. Vitamin D and multiple sclerosis in Asians and Caucasians: environmental and genetic aspects. ACTA ACUST UNITED AC 2013. [DOI: 10.1111/cen3.12058] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
- Masaaki Niino
- Department of Clinical Research; Hokkaido Medical Center; Sapporo Japan
| | - Yusei Miyazaki
- Department of Clinical Research; Hokkaido Medical Center; Sapporo Japan
- Department of Neurology; Hokkaido Medical Center; Sapporo Japan
| | | | - Seiji Kikuchi
- Department of Neurology; Hokkaido Medical Center; Sapporo Japan
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23
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Cui N, Xia W, Su H, Pang L, Jiang Y, Sun Y, Nie M, Xing X, Li M, Wang O, Yuan T, Chi Y, Hu Y, Liu H, Meng X, Zhou X. Novel mutations of CYP27B1 gene lead to reduced activity of 1α-hydroxylase in Chinese patients. Bone 2012; 51:563-9. [PMID: 22588163 DOI: 10.1016/j.bone.2012.05.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/10/2012] [Revised: 05/04/2012] [Accepted: 05/06/2012] [Indexed: 01/08/2023]
Abstract
Pseudovitamin D-deficiency rickets (PDDR) is an autosomal recessive disorder resulting from a defect in renal 25-hydroxyvitamin D 1α-hydroxylase, the key enzyme in the pathway of vitamin D metabolism. We identified ten different mutations in the 1α-hydroxylase gene (CYP27B1) in eight Chinese families with PDDR by DNA-sequence analysis. Six of them are novel missense mutations: G57V, G73W, L333F, R432C, R459C, and R492W; three are novel deletion mutations: c48-60del, c1310delG, and c1446delA; and an insertion mutation c1325-1332insCCCACCC reported previously. Functional assay revealed that the missense mutants identified in this study retain 5.5-12.1% 1α-hydroxylase activity of the wild type. The study describes nine novel mutations in addition to 37 known mutations of CYP27B1 gene and shows the correlation between these mutations and the clinical findings of 1α-hydroxylase deficiency.
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Affiliation(s)
- Ningyi Cui
- Department of Endocrinology, Key Laboratory of Endocrinology, Ministry of Health, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, China
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24
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Durmaz E, Zou M, Al-Rijjal RA, Bircan I, Akçurin S, Meyer B, Shi Y. Clinical and genetic analysis of patients with vitamin D-dependent rickets type 1A. Clin Endocrinol (Oxf) 2012; 77:363-9. [PMID: 22443290 DOI: 10.1111/j.1365-2265.2012.04394.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
CONTEXT Vitamin D-dependent rickets type 1A (VDDR-IA, OMIM 264700) is a rare autosomal recessive disorder and is caused by mutations in the CYP27B1 gene. OBJECTIVES We aim to investigate CYP27B1 mutation in seven patients from four separate families and characterize the genotype-phenotype correlation. METHODS The entire coding region of the CYP27B1 gene was sequenced, and genotype-phenotype correlation among patients was assessed. RESULTS Sequencing analysis identified biallelic CYP27B1 mutations in all patients and monoallelic mutations in their parents. One patient from the first family was compound heterozygous for c.1166G>A (p.Arg389His) and a novel nonsense mutation c.1079 C>A (p.Ser360*). Two patients from the second family were homozygous for a novel splice donor site mutation in intron 1 (c.195 + 2 T>G), causing partial retention of the intron and a shift in the reading frame. Both novel mutations lead to the complete loss of vitamin D1α-hydroxylase activity. Four patients from families 3 and 4 were homozygous for a previously reported duplication mutation in exon 8 (1319-1325dupCCCACCC, Phe443Profs*24). Interestingly, one patient who was presented with severe hypocalcaemia and seizures at 4 months of age as a result of Phe443Profs*24 has improved spontaneously since 11 years of age and does not need regular treatment. Her laboratory tests showed normal serum calcium and 1,25(OH)(2) D after refusing to take medication for 12 months. CONCLUSIONS There is a good genotype-phenotype correlation in VDDR-IA. However, some patients may recover from the loss of CYP27B1 function, probably due to 1α-hydroxylase activity exerted by a non-CYP27B1 enzyme.
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Affiliation(s)
- Erdem Durmaz
- Department of Pediatric Endocrinology, Akdeniz University School of Medicine, Antalya, Turkey
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25
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Ramagopalan SV, Dyment DA, Cader MZ, Morrison KM, Disanto G, Morahan JM, Berlanga-Taylor AJ, Handel A, De Luca GC, Sadovnick AD, Lepage P, Montpetit A, Ebers GC. Rare variants in the CYP27B1 gene are associated with multiple sclerosis. Ann Neurol 2012; 70:881-6. [PMID: 22190362 DOI: 10.1002/ana.22678] [Citation(s) in RCA: 177] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
OBJECTIVE Multiple sclerosis (MS) is a complex neurological disease. Genetic linkage analysis and genotyping of candidate genes in families with 4 or more affected individuals more heavily loaded for susceptibility genes has not fully explained familial disease clustering. METHODS We performed whole exome sequencing to further understand the heightened prevalence of MS in these families. RESULTS Forty-three individuals with MS (1 from each family) were sequenced to find rare variants in candidate MS susceptibility genes. On average, >58,000 variants were identified in each individual. A rare variant in the CYP27B1 gene causing complete loss of gene function was identified in 1 individual. Homozygosity for this mutation results in vitamin D-dependent rickets I (VDDR1), whereas heterozygosity results in lower calcitriol levels. This variant showed significant heterozygous association in 3,046 parent-affected child trios (p = 1 × 10(-5)). Further genotyping in >12,500 individuals showed that other rare loss of function CYP27B1 variants also conferred significant risk of MS, Peto odds ratio = 4.7 (95% confidence interval, 2.3-9.4; p = 5 × 10(-7)). Four known VDDR1 mutations were identified, all overtransmitted. Heterozygous parents transmitted these alleles to MS offspring 35 of 35× (p = 3 × 10(-9)). INTERPRETATION A causative role for CYP27B1 in MS is supported; the mutations identified are known to alter function having been shown in vivo to result in rickets when 2 copies are present. CYP27B1 encodes the vitamin D-activating 1-alpha hydroxylase enzyme, and thus a role for vitamin D in MS pathogenesis is strongly implicated.
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Affiliation(s)
- Sreeram V Ramagopalan
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
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Yan Y, Calikoglu AS, Jain N. Vitamin D-dependent rickets type 1: a rare, but treatable, cause of severe hypotonia in infancy. J Child Neurol 2011; 26:1571-5. [PMID: 21700898 DOI: 10.1177/0883073811411190] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Vitamin D-dependent rickets type 1 is an autosomal recessive disorder caused by an inactivating mutation of the 25-hydroxyvitamin-D-1α-hydroxylase (CYP27B1) gene. Clinical presentation is characterized by early onset of severe rickets and can include severe hypotonia. Here, we report a 16-month-old white male who presented with severe muscle weakness, failure to thrive, renal tubular dysfunction, and skeletal deformities, including osteopenia and multiple fractures. At presentation, he had severe hypocalcemia, hypophosphatemia, hypomagnesemia, and elevated alkaline phosphatase and parathyroid hormone levels, although normal 25-hydroxyvitamin D levels. DNA sequencing of the CYP27B1 gene revealed a novel mutation in exon 2 (c286_300de115) and a previously reported mutation in exon 7 (c.1166G>A). Once calcitriol therapy was initiated, the patient showed significant improvement in muscle strength and linear growth. Serum calcium, phosphorous, and alkaline phosphatase returned to normal range. Organic aciduria resolved and aminoaciduria significantly improved 2 months after parathyroid hormone levels normalized.
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Affiliation(s)
- Yun Yan
- Department of Pediatrics, Division of Pediatric Endocrinology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
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Zou M, Baitei EY, Alzahrani AS, Parhar RS, Al-Mohanna FA, Meyer BF, Shi Y. Mutation prediction by PolyPhen or functional assay, a detailed comparison of CYP27B1 missense mutations. Endocrine 2011; 40:14-20. [PMID: 21604088 DOI: 10.1007/s12020-011-9489-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/07/2011] [Accepted: 05/05/2011] [Indexed: 01/08/2023]
Abstract
Vitamin D-dependent rickets type 1 (VDDR-I) is caused by mutation in CYP27B1. The glycine residue at codon 102 is not conserved between human (G(102)) and rodent (S(102)). G102E mutation results in 80% reduction in its enzymatic activity but PolyPhen predicts benign change. It is not known whether G102S has any damaging effect on 1α-hydroxylase activity. We investigated the effect of CYP27B1 (G102S) on its enzymatic activity and compared mutation prediction accuracy for all known CYP27B1 mutations among three free online protein prediction programs: PolyPhen, PolyPhen-2, and PSIPRED. G102S has no damaging effect on 1α-hydroxylase activity. G102D retained 30% enzymatic activity. All three programs correctly predicted damaging change for G102D. PolyPhen predicted benign change for G102S, whereas PolyPhen-2 and PSIPRED indicated possible damaging effect. Among 24 reported damaging mutations, PSIPRED, PolyPhen-2, and PolyPhen achieved 100%, 91.7% (22/24), and 75% (18/24) accuracy rate, respectively. The residues of incorrectly predicted mutations were not conserved. We conclude that G102D resulted in a significant reduction in 1α-hydroxylase activity, whereas G102S did not. PSIPRED and PolyPhen-2 are superior to PolyPhen in predicting damaging mutations.
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Affiliation(s)
- Minjing Zou
- Department of Genetics (MBC-03), King Faisal Specialist Hospital and Research Centre, P.O. Box 3354, Riyadh, 11211, Saudi Arabia
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Zhao X, Dittmer KE, Blair HT, Thompson KG, Rothschild MF, Garrick DJ. A novel nonsense mutation in the DMP1 gene identified by a genome-wide association study is responsible for inherited rickets in Corriedale sheep. PLoS One 2011; 6:e21739. [PMID: 21747952 PMCID: PMC3128599 DOI: 10.1371/journal.pone.0021739] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2011] [Accepted: 06/09/2011] [Indexed: 01/22/2023] Open
Abstract
Inherited rickets of Corriedale sheep is characterized by decreased growth rate, thoracic lordosis and angular limb deformities. Previous outcross and backcross studies implicate inheritance as a simple autosomal recessive disorder. A genome wide association study was conducted using the Illumina OvineSNP50 BeadChip on 20 related sheep comprising 17 affected and 3 carriers. A homozygous region of 125 consecutive single-nucleotide polymorphism (SNP) loci was identified in all affected sheep, covering a region of 6 Mb on ovine chromosome 6. Among 35 candidate genes in this region, the dentin matrix protein 1 gene (DMP1) was sequenced to reveal a nonsense mutation 250C/T on exon 6. This mutation introduced a stop codon (R145X) and could truncate C-terminal amino acids. Genotyping by PCR-RFLP for this mutation showed all 17 affected sheep were "T T" genotypes; the 3 carriers were "C T"; 24 phenotypically normal related sheep were either "C T" or "C C"; and 46 unrelated normal control sheep from other breeds were all "C C". The other SNPs in DMP1 were not concordant with the disease and can all be ruled out as candidates. Previous research has shown that mutations in the DMP1 gene are responsible for autosomal recessive hypophosphatemic rickets in humans. Dmp1_knockout mice exhibit rickets phenotypes. We believe the R145X mutation to be responsible for the inherited rickets found in Corriedale sheep. A simple diagnostic test can be designed to identify carriers with the defective "T" allele. Affected sheep could be used as animal models for this form of human rickets, and for further investigation of the role of DMP1 in phosphate homeostasis.
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Affiliation(s)
- Xia Zhao
- Department of Animal Science and Center for Integrated Animal Genomics, Iowa State University, Ames, Iowa, United States of America
| | - Keren E. Dittmer
- Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Palmerston North, New Zealand
| | - Hugh T. Blair
- Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Palmerston North, New Zealand
| | - Keith G. Thompson
- Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Palmerston North, New Zealand
| | - Max F. Rothschild
- Department of Animal Science and Center for Integrated Animal Genomics, Iowa State University, Ames, Iowa, United States of America
| | - Dorian J. Garrick
- Department of Animal Science and Center for Integrated Animal Genomics, Iowa State University, Ames, Iowa, United States of America
- Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Palmerston North, New Zealand
- * E-mail:
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29
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Kim CJ. Vitamin D dependent rickets type I. KOREAN JOURNAL OF PEDIATRICS 2011; 54:51-4. [PMID: 21503197 PMCID: PMC3077501 DOI: 10.3345/kjp.2011.54.2.51] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/18/2011] [Accepted: 01/31/2011] [Indexed: 01/14/2023]
Abstract
Vitamin D is present in two forms, ergocalciferol (vitamin D2) produced by plants and cholecalciferol (vitamin D3) produced by animal tissues or by the action of ultraviolet light on 7-dehydrocholesterol in human skin. Both forms of vitamin D are biologically inactive pro-hormones that must undergo sequential hydroxylations in the liver and the kidney before they can bind to and activate the vitamin D receptor. The hormonally active form of vitamin D, 1,25-dihydroxyvitamin D3 [1,25(OH)2D], plays an essential role in calcium and phosphate metabolism, bone growth, and cellular differentiation. Renal synthesis of 1,25(OH)2D from its endogenous precursor, 25-hydroxyvitamin D (25OHD), is the rate-limiting and is catalyzed by the 1α-hydroxylase. Vitamin D dependent rickets type I (VDDR-I), also referred to as vitamin D 1α-hydroxylase deficiency or pseudovitamin D deficiency rickets, is an autosomal recessive disorder characterized clinically by hypotonia, muscle weakness, growth failure, hypocalcemic seizures in early infancy, and radiographic findings of rickets. Characteristic laboratory features are hypocalcemia, increased serum concentrations of parathyroid hormone (PTH), and low or undetectable serum concentrations of 1,25(OH)2D despite normal or increased concentrations of 25OHD. Recent advances have showed in the cloning of the human 1α-hydroxylase and revealed mutations in its gene that cause VDDR-I. This review presents the biology of vitamin D, and 1α-hydroxylase mutations with clinical findings.
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Affiliation(s)
- Chan Jong Kim
- Department of Pediatrics, Chonnam National University Medical School, Gwangju, Korea
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