Dataset Information

Identification of five novel mutations in the long isoform of the USH2A gene in Chinese families with Usher syndrome type II.

ABSTRACT: PURPOSE: Usher syndrome type II (USH2) is the most common form of Usher syndrome, an autosomal recessive disorder characterized by moderate to severe hearing loss, postpuberal onset of retinitis pigmentosa (RP), and normal vestibular function. Mutations in the USH2A gene have been shown to be responsible for most cases of USH2. To further elucidate the role of USH2A in USH2, mutation screening was undertaken in three Chinese families with USH2. METHODS: Three unrelated Chinese families, consisting of six patients and 10 unaffected relatives, were examined clinically, and 100 normal Chinese individuals served as controls. Genomic DNA was extracted from the venous blood of all participants. The coding region (exons 2-72), including the intron-exon boundary of USH2A, was amplified by polymerase chain reaction (PCR). The PCR products amplified from the three probands were analyzed using direct sequencing to screen sequence variants. Whenever substitutions were identified in a patient, restriction fragment length polymorphism analysis, or single strand conformation polymorphism analysis was performed on all available family members and the control group. RESULTS: Fundus examination revealed typical fundus features of RP, including narrowing of the vessels, bone-speckle pigmentation, and waxy optic discs. The ERG wave amplitudes of three probands were undetectable. Audiometric tests indicated moderate to severe sensorineural hearing impairment. Vestibular function was normal. Five novel mutations (one small insertion, one small deletion, one nonsense, one missense, and one splice site) were detected in three families after sequence analysis of USH2A. Of the five mutations, four were located in exons 22-72, specific to the long isoform of USH2A. CONCLUSIONS: The mutations found in our study broaden the spectrum of USH2A mutations. Our results further indicate that the long isoform of USH2A may harbor even more mutations of the USH2A gene.

SUBMITTER: Dai H

PROVIDER: S-EPMC2584772 | biostudies-literature | 2008

REPOSITORIES: biostudies-literature

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Identification of five novel mutations in the long isoform of the USH2A gene in Chinese families with Usher syndrome type II.

Dai Hanjun H Zhang Xiaohui X Zhao Xin X Deng Ting T Dong Bing B Wang Jingzhao J Li Yang Y

Molecular vision 20081117

<h4>Purpose</h4>Usher syndrome type II (USH2) is the most common form of Usher syndrome, an autosomal recessive disorder characterized by moderate to severe hearing loss, postpuberal onset of retinitis pigmentosa (RP), and normal vestibular function. Mutations in the USH2A gene have been shown to be responsible for most cases of USH2. To further elucidate the role of USH2A in USH2, mutation screening was undertaken in three Chinese families with USH2.<h4>Methods</h4>Three unrelated Chinese famil ...[more]

PMID: 19023448

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Project description:PurposeTo describe the clinical and genetic findings in one Chinese family with autosomal recessive retinitis pigmentosa (arRP) and in three unrelated Chinese families with Usher syndrome type II (USH2).MethodsOne family (FR1) with arRP and three unrelated families (F6, F7, and F8) with Usher syndrome (USH), including eight affected members and seven unaffected family individuals were examined clinically. The study included 100 normal Chinese individuals as normal controls. After obtaining informed consent, peripheral blood samples from all participants were collected and genomic DNA was extracted. Genotyping and haplotyping analyses were performed on the known genetic loci for arRP with a panel of polymorphic markers in family FR1. In all four families, the coding region (exons 2-72), including the intron-exon boundary of the USH2A (Usher syndrome type -2A protein) gene, was screened by PCR and direct DNA sequencing. Whenever substitutions were identified in a patient, a restriction fragment length polymorphism (RFLP) analysis, single strand conformation polymorphism (SSCP) analysis, or high resolution melt curve analysis (HRM) was performed on all available family members and on the 100 normal controls.ResultsThe affected individuals presented with typical fundus features of retinitis pigmentosa (RP), including narrowing of the vessels, bone-spicule pigmentation, and waxy optic discs. The electroretinogram (ERG) wave amplitudes of the available probands were undetectable. Audiometric tests in the affected individuals in family FR1 were normal, while indicating moderate to severe sensorineural hearing impairment in the affected individuals in families F6, F7, and F8. Vestibular function was normal in all patients from all four families. The disease-causing gene in family FR1 was mapped to the USH2A locus on chromosome 1q41. Seven novel mutations (two missenses, one 7-bp deletion, two small deletions, and two nonsenses) were detected in the four families after sequencing analysis of USH2A.ConclusionsThe results further support that mutations of USH2A are also responsible for non-syndromic RP. The mutation spectrum among Chinese patients might differ from that among European Caucasians.

Dataset Information

Identification of five novel mutations in the long isoform of the USH2A gene in Chinese families with Usher syndrome type II.

Publications

Identification of five novel mutations in the long isoform of the USH2A gene in Chinese families with Usher syndrome type II.

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