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This paper presents a mutation as well as a genotype–phenotype analysis of the GJB2 and GJB6 genes in 476 samples from non-syndromic unrelated Argentinean deaf patients (104 familial and 372 sporadic cases). Most of them were of prelingual onset (82 %) and 27 % were cochlear implanted. Variation of sequences was detected in 171 of the 474 patients (36 %). Overall, 43 different sequence variations were identified in GJB2 and GJB6. Four of them are reported for the first time in GJB2: c.233dupG, p.Ala78Ser, p.Val190Asp and p.Cys211Tyr. Mutations in GJB6 were detected in 3 % of patients [nine del(GJB6-D13S1830) and three del(GJB6-D13S1854)]. Of the 43 different variations identified in GJB2, 6 were polymorphisms and of the others, 10 (27 %) were truncating and 27 (73 %) were nontruncating. Patients with two truncating mutations had significantly worse hearing impairment than all other groups. Moderate phenotypes were observed in a group of patients carrying biallelic mutations (23 %). This work shows the high prevalence of GJB2 mutations in the Argentinean population and presents an analysis of moderate phenotypes in our cohort. [ABSTRACT FROM AUTHOR]

Mutations in the GJB2 gene are responsible for more than half of all cases of recessive non-syndromic deafness. This article presents a mutation analysis of the GJB2, GJB6, OTOF and MTRNR1 genes in 252 patients with sensorineural non-syndromic hearing loss. Thirty-one different mutations were identified in GJB2 and GJB6 in 86 of the 252 (34%) patients. We describe for the first time two new mutations in GJB2: the missense mutation c.29 T>C (p.Leu10Pro) in the N terminal domain and c.326 G>T (p.Gly109Val) in the intracytoplasmic domain of connexin 26. This work shows the high prevalence of GJB2 mutations in the Argentinean population, with frequencies that are comparable to those of the Mediterranean area. Most important, it adds two novel GJB2 mutations to be taken into consideration in the genetic diagnosis of non-syndromic sensorineural hearing loss. Copyright © 2009 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Conclusion: There were no apparent differences in speech performance after cochlear implantation between patients with biallelic GJB2 and/or GJB6 mutations and those with deafness of unknown aetiology. These data have important implications for the selection of prognostic indicators of the outcome of cochlear implantation. Objective: To compare performance after cochlear implantation in children with mutations in GJB2 (connexin 26) and/or GJB6 (connexin 30) and children with deafness of unknown aetiology. Subjects and methods: Genetic analysis and speech performance evaluation was determined in 24 patients with (n=11) and without (n=13) biallelic GJB2 and/or GJB6 mutations who underwent cochlear implantation. Speech perception skills were measured 12 and 24 months after surgery. Each patient was classified in accordance with the speech perception category (SPC). Results: Overall, the two groups showed similar significant improvement in speech perception after implantation. [ABSTRACT FROM AUTHOR]