Investigation of the GJB2 gene Mutations among Subjects with Non-Syndromic Sensorineural Hearing Loss

Hearing impairment as a heterogeneous disorder is the most common sensory defect that occur 1 in 1000. Mutations in GJB2 (CX26) gene at DFNB1 locus on 13q12 are responsible for autosomal recessive non-syndromic hearing loss (ARNSHL) in many populations. This study investigates the GJB2 gene mutations in deaf patients refereed to the deaf center of Tabriz.
In the present descriptive- laboratory study, 50 patients with NSHL were selected from the deaf center of Tabriz, Iran. After taking 5 ml blood samples (5ml) from the patients, genomic DNA was extracted using the Rapid Genomic DNA Extraction (RGDE) method. In this study, detection of common mutation in GJB2 gene (35delG) using AS-PCR method and other mutations with direct sequencing of amplified fragments of coding region was performed.
In this study, only 35delG mutation was observed in the GJB2 gene. From 50 deaf persons, 16 patients (32%) were homozygous, 7 patients (14%) were heterozygous and 27 patients (54%) were normal for 35delG mutation. In heterozygous and normal individuals for 35delG mutation, another mutation was not observed. Therefore, the frequency of 35delG in the study population is 39%.
The results of this study show that, 35delG mutation is the most common mutation in the cause of hearing loss in the patients, but other genes are involved in the pathogenesis of deafness and further studies are needed to identify them. Therefore, mutation screening of individuals with hearing loss referred to genetic counseling centers before marriage and pregnancy is recommended.