title: 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.
abstract: 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.
authors.affiliation: Servei de Genètica, Universidad de Vigo, Vigo, Spain.
authors.forename: S
authors.initials: S
authors.lastname: Bernal
authors.forename: C
authors.initials: C
authors.lastname: Medà
authors.forename: T
authors.initials: T
authors.lastname: Solans
authors.forename: C
authors.initials: C
authors.lastname: Ayuso
authors.forename: B
authors.initials: B
authors.lastname: Garcia-Sandoval
authors.forename: D
authors.initials: D
authors.lastname: Valverde
authors.forename: E
authors.initials: E
authors.lastname: Del Rio
authors.forename: M
authors.initials: M
authors.lastname: Baiget
mesh_terms: D000328:Adult; D002648:Child; D018389:Codon, Nonsense; D004252:DNA Mutational Analysis; D016326:Extracellular Matrix Proteins / Q000235:genetics*; D005260:Female; D016368:Frameshift Mutation; D005787:Gene Frequency; D005838:Genotype; D006319:Hearing Loss, Sensorineural / Q000235:genetics*; D006801:Humans; D008297:Male; D009154:Mutation; D020125:Mutation, Missense; D010375:Pedigree; D010641:Phenotype; D011110:Polymorphism, Genetic; D012174:Retinitis Pigmentosa / Q000235:genetics*; D013030:Spain; D013577:Syndrome
chemical_list: D018389:Codon, Nonsense; D016326:Extracellular Matrix Proteins; C112735:USH2A protein, human