Analysis of Common Mutations in GJB۲ and GJB۶ Genes in Patients with Autosomal Recessive Non-syndromic Hearing Loss in Eastern Azarbaijan

Background and Objective: Profound hearing loss is one of the most prevalent congenital disorders affecting about ۱ in ۱۰۰۰ 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 GJB۲ (connexin ۲۶) and GJB۶ (connexin ۳۰) genes located at DFNB۱ locus of chromosome۱۳q. 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 GJB۲ gene (۳۵delG) and a mutation of GJB۶ gene (del(GJB۶-D۱۳S۱۸۳۰)) were analyzed in ۱۲۹ referring patients with ARNSHL using ARMS-PCR and multiplex-PCR techniques, respectively. These methods facilitate analyzing parents and carriers. Results: ۲۱% of the studied families had ۳۵delG mutation in connexin ۲۶ gene. ۳۶ chromosomes (۱۸%) out of ۲۰۰ studied chromosomes had ۳۵delG mutation while none of the chromosomes had del(GJB۶-D۱۳S۱۸۳۰) mutation in connexin ۳۰. The ۳۵delG mutation was assessed in parents and siblings in order to detect carriers. Conclusion: ۳۵delG mutation accounts for ۱۸% of ARNSHL in eastern Azerbaijan which is various to other published studies from different regions of Iran. The absence of del(GJB۶-D۱۳S۱۸۳۰) mutation in the patients may be due to the founder effect.

Keywords:

ARNSHL , GJB۲ , GJB۶ , Eastern Azarbaijan