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Clinical and genetic studies in Spanish patients with Usher syndrome type II: description of new mutations and evidence for a lack of genotype–phenotype correlation
Author(s) -
Bernal S,
Medà C,
Solans T,
Ayuso C,
GarciaSandoval B,
Valverde D,
Del Rio E,
Baiget M
Publication year - 2005
Publication title -
clinical genetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.543
H-Index - 102
eISSN - 1399-0004
pISSN - 0009-9163
DOI - 10.1111/j.1399-0004.2005.00481.x
Subject(s) - usher syndrome , retinitis pigmentosa , genetics , allele , genotype , biology , phenotype , genotype phenotype distinction , mutation , hearing loss , exon , allelic heterogeneity , gene , medicine , audiology
Patients with Usher syndrome type II (USH2) show moderate‐to‐severe hearing loss (HL), retinitis pigmentosa and normal vestibular function. The progression of HL remains controversial. To evaluate whether a phenotype–genotype correlation exists regarding the issue of progression of HL, only USH2 patients with a defined genotype were selected. Ophthalmologic, vestibular and audiometric examination along with a mutation analysis of the USH2A gene (exons 1–21) was performed in twenty‐eight Spanish USH2 patients. Ten different pathogenic mutations and 17 sequence variants not associated with the disease were found. Six of the 10 mutations are novel. Disease alleles were identified in 13 of the 28 families tested. Eight of these 13 families had a mutation found in both alleles. In the other five families, only one mutation was identified. The phenotypic data provide evidence for the existence of phenotypic differences between patients with the same genotype. These differences were observed at both the interfamilial and intrafamilial levels.