Mutation in gap and tight junctions in patients with non-syndromic hearing loss.

Biallelic mutations in the GJB2, GJB3, GJB6 and CLDN14 genes have been implicated in autosomal recessive non-syndromic hearing impairment (ARNSHI). Moreover, a large number of GJB2 heterozygous patients was reported. The phenotype was in partly justified by the occurrence of two deletions including GJB6. We analysed GJB2, GJB6, GJB3 and CLDN14 in 102 Tunisian patients with ARNSHI. The deletions del(GJB6-D13S1830) and del(GJB6-D13S1854) were also screened. The c.35delG in GJB2 was the most frequent mutation (21.57%). It was detected at heterozygous state in 2 patients. The del(GJB6-D13S1830) was identified in one case at heterozygous state. No other mutation in studied gap junction genes was detected in heterozygous patients. Several polymorphisms were identified in GJB3, GJB6 and CLDN14. Our study confirms the importance of GJB2 screening in ARNSHI and suggests that in consanguineous populations, a single DFNB1 mutant allele in individuals with HI is likely due to a coincidental carrier state.