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

Frequency of a very rare 35delG mutation in two ethnic groups of iranian population

The 35delG mutation in the Connexin 26 gene [Cx26], at the DNFB1 locus is the most common mutation in the patients with autosomal recessive non-syndromic hearing loss [ARNSHL]. We have studied a total of 224 deaf cases from 189 families in two populations of Iran [Sistan va Bluchestan and Hormozgan provinces] by prescreening nested PCR, polyacrylamide gel electrophoresis and consequent direct sequencing method for all cases. The aim of the present work was to find prevalence of GJB2 mutations in the populations studied. Four different GJB2 mutations including 35delG, W24X, R127H and [V27I + E114 G] were identified in 11 of 189 families [5.8%]. Two polymorphisms [V27I and V153I] also were detected in 14 families. A polymorphism S86T was determined in all cases. Homozygote 35delG mutation was found only in 1 of 189 families [0.5%].The rate of Cx26 mutations found in this study was lower than other Iranian populations. So the cause of deafness in the populations studied remains to be detected in other loci or genes