Familial and Sporadic GJB2-Related Deafness in Iran: Review of Gene Mutations

Background: Mutations in the GJB 2 gene encoding connexin 26 protein, are the main cause for autosomal recessive and sporadic non syndromic hearing loss in many populations. Here , we have taken together and reviewed results from our six prev ious publications, our unpubli shed data from ten Iranian provinces, as well as data from two previou s mutation reports to provide a comprehensive collection of data for GJB2 mutations and deafness in Iran. Methods: In all, 1095 hear ing impaired stud ents and their deaf siblings from 890 famili es in 10 provinces of Iran were studied. The prev alence and type of the GJB2 gene mutations were investigated using nested peR pre scre ening strategy and direct sequencing of the codin g exon of the gene. Results: Altogether 31 different genetic variants were detected from which 17 GJB2 mutat ions were identified. GJB2 mutations were found in 14.6% of deaf families (18 .29% of familial and 12.7% of sporadic cases). We found GJB2 mutati ons in both allel es in 78% of GJB2 mutations chromosomes. However, 35deiG mutation was the most common Gffi2 mutation accounting for 74.5% of the mutati ons in populations studied. Conclusion: Our data indicated that a spec ific combination of GJB2 mutations type s and frequencies was presented in different populations of Iran . These results also highli ght the importance of GJB2 mutations in development of hearin g loss in familial and sporadic deaf families in different parts of the country and can be used as a basis of genet ic counselin g and clin ical guideline in Iran.