Detection of single-nucleotide polymorphism Gap junction protein Beta-2 genes in deaf schoolchildren of javanese population in Surabaya, Indonesia

Background: Genetic factors account for about 50%-75% responsible for hearing loss. The existence of single-nucleotide polymorphism (SNP) as genetic factors that affect hereditary hearing loss. The widely studied SNP was the gap junction protein beta-2 (GJB2) gene encoding the gap junction beta-2 protein (connexin26) that found in cochlea and required to convert sound waves into electrical nerve impulse. This study was aimed to detect the SNP GJB2 gene of hereditary hearing loss patients from Javanese population in Surabaya, Indonesia. Methods: The design of this study was a cross-sectional, analytic observational. The participant was taken randomly among the students from a deaf School in Surabaya. The questionnaire was completed by the parents of the deaf children. Blood sampling was taken from venous peripheral blood. DNA was extracted and amplified on GJB2 gene area by polymerase chain reaction (PCR). The positive results of PCR were processed further for sequencing. The sequencing results were analyzed to detect the GJB2 gene SNP with reference sequence/rs-80338939. Results: A total of 22 children participated in this study; all were profound sensorineural hearing loss (SNHL). The hereditary hearing loss was obtained with fewer in five children (22.73%), who had a history of hearing loss in their family. It was compared to 17 children (77.27%) who had no family history of hearing loss. It was found that the nucleotide variation in nucleotide number 8473 of GJB2 gene as much as 3 (13.64%) out of 22 children in hereditary hearing loss patients in Deaf School Type B Surabaya. Conclusions: This study did not found any SNP GJB2 gene (rs-80338939) of hereditary hearing loss patients from the Javanese population in Surabaya, Indonesia. There was the nucleotide substitution G to A in nucleotide number 8473 of GJB2 gene, which indicated the change of amino acid code genetic code table (valine) to amino acid code genetic code table (isoleucine). It may as the cause of SNHL.