Spectrum and Frequency of GJB2 Mutations in a Cohort of 264 Portuguese Nonsyndromic Sensorineural Hearing Loss Patients

• Autor(a) principal: Matos, T
• Data de Publicação: 2013
• Outros Autores: Simões-Teixeira, H, Caria, H, Gonçalves, AC, Chora, J, Correia, MC, Moura, C, Rosa, H, Monteiro, L, O'Neill, A, Dias, O, Andrea, M, Fialho, G
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10400.17/2497
• topic: Audiometry; Connexins; DNA Mutational Analysis; Exons; Gene Frequency; Genetic Predisposition to Disease; Hearing Loss, Sensorineural; Humans; Otoscopy; Phenotype; Portugal; RNA Splice Sites; Severity of Illness Index; Mutation; HDE ORL

OBJECTIVE: To assess the spectrum and prevalence of mutations in the GJB2 gene in Portuguese nonsyndromic sensorineural hearing loss (NSSHL) patients. DESIGN: Sequencing of the coding region, basal promoter, exon 1, and donor splice site of the GJB2 gene; screening for the presence of the two common GJB6 deletions. STUDY SAMPLE: A cohort of 264 Portuguese NSSHL patients. RESULTS: At least one out of 21 different GJB2 variants was identified in 80 (30.2%) of the 264 patients analysed. Two mutant alleles were found in 53 (20%) of these probands, of which 83% (44/53) harboured at least one c.35delG allele. Twenty-seven (10.2%) of the probands harboured only one mutant allele. Subsequent analysis revealed that the GJB6 deletion del(GJB6-D13S1854) was present in at least 7.4% (2/27) of the patients carrying only one mutant GJB2 allele. Overall, one in five (55/264) of the patients were diagnosed as having DFNB1-related NSSHL, of which the vast majority (53/55) harboured only GJB2 mutations. CONCLUSIONS: This study provides clear demonstration that mutations in the GJB2 gene are an important cause of NSSHL in Portugal, thus representing a valuable indicator as regards therapeutical and rehabilitation options, as well as genetic counseling of these patients and their families.