Background and Objective: Profound hearing loss is one of the most prevalent congenital disorders affecting about 1 in 1000 newborns. Autosomal recessive non-syndromic hearing loss (ARNSHL) is the predominant form of the severe inherited childhood deafness. This type of hearing loss in one-half of the cases is caused by mutations in GJB2 (connexin 26) and GJB6 (connexin 30) genes located at DFNB1 locus of chromosome13q. Protein products of the two above-mentioned genes play a crucial role in the intercellular communications within the inner ear through gap junction. This study was conducted to analyze the two most common mutations among ARNSHL patients referring to the Genetics center of Tabriz, eastern Azarbaijan.
Materials & Methods: The most common mutation of GJB2 gene (35delG) and a mutation of GJB6 gene (del(GJB6-D13S1830)) were analyzed in 129 referring patients with ARNSHL using ARMS-PCR and multiplex-PCR techniques, respectively. These methods facilitate analyzing parents and carriers.
Results: 21% of the studied families had 35delG mutation in connexin 26 gene. 36 chromosomes (18%) out of 200 studied chromosomes had 35delG mutation while none of the chromosomes had del(GJB6-D13S1830) mutation in connexin 30. The 35delG mutation was assessed in parents and siblings in order to detect carriers.
Conclusion: 35delG mutation accounts for 18% of ARNSHL in eastern Azerbaijan which is various to other published studies from different regions of Iran. The absence of del(GJB6-D13S1830) mutation in the patients may be due to the founder effect.