Spectrum of GJB2 (Cx26) gene mutations in Iranian Azeri patients with nonsyndromic autosomal recessive hearing loss

Objective: Hereditary hearing impairment is a genetically heterogeneous disorder. In spite of this,mutations in the GJB2 gene, encoding connexin 26 (Cx26), are a major cause of nonsyndromic recessivehearing loss in many countries and are largely dependent on ethnic groups. The purpose of our study wasto characterize the type and prevalence of GJB2 mutations among Azeri population of Iran.Methods: Fifty families presenting autosomal recessive nonsyndromic hearing loss from Ardabilprovince of Iran were studied for mutations in GJB2 gene. All DNA samples were screened for c.35delGmutation by ARMS PCR. Samples from patients who were normal for c.35delG were analyzed for theother variations in GJB2 by direct sequencing. In the absence of mutation detection, GJB6 was screenedfor the del(GJB6-D13S1830) and del(GJB6-D13S1854).Result: Thirteen families demonstrated alteration in the Cx26 (26%). The 35delG mutation was the mostcommon one, accounting for 69.2% (9 out of 13 families). All the detected families were homozygous forthis mutation. Two families were homozygous for delE120 and 299–300delAT mutations. We alsoidentified a novel mutation: c.463–464 delTA in 2 families resulting in a frame shift mutation.Conclusion: Our results suggest that c.35delG mutation in the GJB2 gene is the most important cause ofGJB2 related deafness in Iranian Azeri population