GJB2 (Connexin 26) mutations analysis in patients with congenital non-syndromic sensorineural hearing loss

Hearing loss is one of the most frequent sensorial defects that causes limit social and intellectual development. İn this study we aimed to search GJB2 (connexin 26) gene mutations in patients with certain types of congenital hearing loss in our geographic area.The study group consisted of 60 patients with congenital, non-syndromic sensorineural deafness diagnosed at the Firat University Faculty of Medicine ENT Department. To the control group 60 patients without hearing trouble were assigned. A 3 ml venous blood sample was drawn from all subjects to analized by the Medical Biology and Genetics Department of Firat University Faculty of Medicine. This analyses contained searching GJB6 and 35delG, 167delT, delE120, 235delC of the GJB2 gene mutations. DNA sequencing to screening for other new mutations was also performed.Mutations were found in six (10%) patients of the study group, five patients with 35delG mutation (8.3%) and one patient with delE120 (1.7%). None of the other GJB6 mutations mentioned above were seen. No mutations were found in any of the control subjects. A statistically significant correlation (p<0.05) was detected between family history of hearing loss and 35delG or delE120 mutations.To conclude, 35delG was the most frequent mutation, as expected from published reports, this is the first study of GJB2 mutations in our geographic area. Genetic counseling of patients with congenital, non-syndromic sensorineural deafness and their families is extremely important for determining the etiology of the hearing loss and identifying heterozygotic and homozygotic individuals through genetic testing.Key Words: Congenital hearing loss, Autosomal recessive, GJB2