Dataset Information

A genetic analysis of 23 Chinese patients with hemophilia B.

ABSTRACT: Hemophilia B (HB) is an X-linked recessive bleeding disorder caused by mutations in the coagulation factor IX (FIX) gene. Genotyping patients with HB is essential for genetic counseling and provides useful information for patient management. In this study, the F9 gene from 23 patients with HB was analyzed by direct sequencing. Nineteen point mutations were identified, including a novel missense variant (c.520G?>?C, p.Val174Leu) in a patient with severe HB and a previously unreported homozygous missense mutation (c.571C?>?T, p.Arg191Cys) in a female patient with mild HB. Two large F9 gene deletions with defined breakpoints (g.10413_11363del, g.12163_23369del) were identified in two patients with severe HB using a primer walking strategy followed by sequencing. The flanking regions of the two breakpoints revealed recombination-associated elements (repetitive elements, non-B conformation forming motifs) with a 5-bp microhomology in the breakpoint junction of g.12163_23369del. These findings imply that non-homologous end joining and microhomology-mediated break-induced replication are the putative mechanisms for the deletions of the F9 gene. Because the g.12163_23369del deletion caused exons to be absent without a frameshift mutation occurring, a smaller FIX protein was observed in western blot analyses.

SUBMITTER: Wang QY

PROVIDER: S-EPMC4842959 | biostudies-literature | 2016 Apr

REPOSITORIES: biostudies-literature

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A genetic analysis of 23 Chinese patients with hemophilia B.

Wang Qing-Yun QY Hu Bei B Liu Hui H Tang Liang L Zeng Wei W Wu Ying-Ying YY Cheng Zhi-Peng ZP Hu Yu Y

Scientific reports 20160425

Hemophilia B (HB) is an X-linked recessive bleeding disorder caused by mutations in the coagulation factor IX (FIX) gene. Genotyping patients with HB is essential for genetic counseling and provides useful information for patient management. In this study, the F9 gene from 23 patients with HB was analyzed by direct sequencing. Nineteen point mutations were identified, including a novel missense variant (c.520G > C, p.Val174Leu) in a patient with severe HB and a previously unreported homozygous m ...[more]

PMID: 27109384

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Project description:AimDe novo DDX3X variants account for 1-3% of unexplained intellectual disability cases in females and very rarely in males. Yet, the clinical and genetic features of DDX3X neurodevelopmental disorder in the Chinese cohort have not been characterized.MethodA total of 23 Chinese patients (i.e., 22 female and 1 male) with 22 de novo DDX3X deleterious variants were detected among 2,317 probands with unexplained intellectual disability (ID) undertaking whole exome sequencing (WES). The age, sex, genetic data, feeding situation, growth, developmental conditions, and auxiliary examinations of the cohort were collected. The Chinese version of the Gesell Development Diagnosis Scale (GDDS-C) was used to evaluate neurodevelopment of DDX3X patients. The Social Communication Questionnaire (SCQ)-Lifetime version was applied as a primary screener to assess risk for autism spectrum disorder (ASD).ResultA total of 17 DDX3X variants were novel and 22 were de novo. Missense variants overall were only slightly more common than loss-of-function variants and were mainly located in two functional subdomains. The average age of this cohort was 2.67 (±1.42) years old. The overlapping phenotypic spectrum between this cohort and previously described reports includes intellectual disability (23/23, 100%) with varying degrees of severity, muscle tone abnormalities (17/23, 73.9%), feeding difficulties (13/23, 56.5%), ophthalmologic problems (11/23, 47.8%), and seizures (6/23, 26.1%). A total of 15 individuals had notable brain anatomical disruption (15/23, 65.2%), including lateral ventricle enlargement, corpus callosum abnormalities, and delayed myelination. Furthermore, 9 patients showed abnormal electroencephalogram results (9/23, 39.1%). Hypothyroidism was first noted as a novel clinical feature (6/23, 26.1%). The five primary neurodevelopmental domains of GDDS-C in 21 patients were impaired severely, and 13 individuals were above the "at-risk" threshold for ASD.InterpretationAlthough a certain degree of phenotypic overlap with previously reported cohorts, our study described the phenotypic and variation spectrum of 23 additional individuals carrying DDX3X variants in the Chinese population, adding hypothyroidism as a novel finding. We confirmed the importance of DDX3X as a pathogenic gene in unexplained intellectual disability, supporting the necessity of the application of WES in patients with unexplained intellectual disability.

Dataset Information

A genetic analysis of 23 Chinese patients with hemophilia B.

Publications

A genetic analysis of 23 Chinese patients with hemophilia B.

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