Autosomal recessive and sporadic non syndromic hearing loss and the incidence of Cx26 mutations in a Province of Iran

Despite the enormous heterogeneity of genetic hearing loss, mutations in the GJB2 [connexin 26] gene located on 'DFNB1' locus [13q12] account for up to 50% of cases of autosomal recessive non-syndromic hearing loss [ARNSHL] in some populations. This study describes the analysis of 100 autosomal recessive and sporadic nonsyndromic hearing loss individuals from 79 families each having at least one deaf child in Chehar Mahal va Bakhtiari province in west of Iran. We have investigated the prevalence of the connexin 26 gene mutations using nested PCR strategy to screen the predominant 35delG mutation and subsequent direct sequencing to detect other Cx26 mutations. Seven different genetic variants were detected from which one novel variant was including 363delC. The 35delG was the most common mutation found in 5 of 79 families [6.3%]. Cx26 related deafness mutations [35delG, [V27I; E114G]] and R127H] were found in 12 of 158 chromosomes studied [7.8%]. We conclude that the association of Cx26 mutations with deafness in Chehar Mahal va Bakhtiari province is low and looks like most other populations of Iran

Report of a new mutation and frequency of connexin 26 gene [GJB2] mutations in patients from three provinces of Iran

Autosomal recessive and sporadic non-syndromic hearing loss [ARSNSHL] is the major form of hereditary deafness.Mutations in the GJB2 gene encoding the gap-junction protein Connexin 26 have been identified to be highly associated with ARSNSHL. In this study we have analyzed 196 deaf subjects from 179 families having one or more deaf children in 3 proviences of Iran, including Kordestan, Khuzestan and Golestan. The nested PCR prescreening strategy and direct sequencing technique were used to detect the mutations in coding exon of the gene. Altogether 3 GJB2 recessive mutations including 35delG, 167delT and V27I+E114G, were identified in 23 of 179 families [12.8%]. Fourteen of 179 families were observed to have GJB2 mutation in both alleles [7.8%]. A novel variant [R159H] also was found in a deaf family from Khuzestan. Four polymorphisms V27I, E114G, S86T and V153 I also were detected in 7 families. A polymorphism [S86T] was seen in the whole population studied. Our data indicated that the rate of connexin 26 mutations is different in this three Irainian population and is lower than the high frequency of 35delG [26%] reported from Gilan province in the north of Iran