Mutation Analysis of FamilialGJB2-Related Deafness in Iranian Azeri Turkish Patients

Abstract

Mutations in the GJB2 gene-encoding connexin 26 protein are the main cause for autosomal recessive nonsyndromic hearing loss worldwide. In this study, we assessed the contributions made by GJB2 and del(GJB6-D13S1830) mutations to the autosomal recessive nonsyndromic deafness genetic load in Iranian Azeri Turkish patients. Probands from 209 different nuclear families were investigated. GJB2 mutations were found in 28% of the patients. Among these patients 44 families had 35delG mutation. The following GJB2 variants, R184P, DelE120, V27I+E114G, W24 x, DelE119, R127H, 235DelC, 290-291 insA, Y155 x, A171T, E147 x, 35insG, G158S, R32H, R143Q, T123N, R143W, H16R, V153I, V27I, M163V, and F154F (a new variant), were identified in 126 of the 418 chromosomes. R143Q mutation was identified as compound heterozygous with 35delG in one profoundly deaf patient. Both parents of this patient were healthy, and one normal sister of this patient was also a carrier for the R143Q, indicating that this mutation has incomplete penetrance. Our results show that GJB2 mutations are responsible for about 28% of the autosomal recessive nonsyndromic hearing loss in this ethnic group. 35delG is the most prevalent GJB2 mutation accounting for 64.5% of the GJB2 mutations.