The GJB2 gene mutation profiles in hearing ımpaired patients from Western Turkey, Canakkale

Abstract

It is reported that 60% of congenital bilateral sensorineural hearing loss is caused by genetic factors, and half of hearing loss at a later stage is due to a single gene mutation. In this study; it is aimed to investigate the hearing loss molecular etiology of GJB2 gene mutations in patients with hearing loss. Forty-six patients who had 90 decibels and above-bilateral sensorineural hearing loss were included. DNAs of the patients were isolated from peripheral blood-EDTA samples. By using PCR primers, specific for the 1st and 2nd GJB2 gene regions, changes in the selected gene regions were investigated by DNA sequence analysis. When 46 patients with hearing loss (5 female, 41 male) were examined, pathological variation was found in 6 patients (13%) and any variation was found in 11 patients (24%). Mutations detected in the cases include heterozygous 35delG (a frameshift mutation in GJB2), heterozygous V153I and V27I (missense mutations in GJB2); and the homozygous H100P variation. No mutation was detected in the 1st exon of GJB2 gene. In the second exon of GJB2 gene; heterozygous 35delG mutation in 2 patients (4.3%), the heterozygous V27I mutation in 2 patients (4.3%), the heterozygous V153I mutation in 2 patients (4.3%) and homozygous H100P alteration in 33 patients (71.7%) were found. The variation we most frequently observed in cases following GJB2 gene sequencing was homozygous H100P alteration; This variation was assessed as polymorphism (71.7%). However, in order to determine if this variation might be related to hearing loss, it was planned to determine the presence of the H100P alteration in control group with complete healthy hearing.