A Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) Analysis of Connexin 26 (GJB2) Gene Common Mutation (235delC) In Indonesian Patients with Prelingual Nonsyndromic Sensorineural Hearing Loss: A Preliminary Study

Background: Inherited hearing impairment affects about 1 in 1000 newborns. Up to 50 percent of all patients with autosomal recessive nonsyndromic prelingual deafness in many populations have mutations in the gene encoding the gap junction protein connexin 26 (GJB2) at locus DFNB1 (autosomal recessive nonsyndromic deafness) on chromosome 13q11-12. In East Asia, there is a common mutation (235delC) of connexin 26 (GJB2) gene mutation, and a common GJB2 gene mutation (V37I) in Singapore and Malaysia with congenital deafness. No connexin 26 gene study was done in Indonesia. In this preliminary study, we analyzed 40 Indonesian patients with prelingual nonsyndromic sensorineural hearing loss. Objective: To detect the common frameshift mutation (235delC) of connexin 26 (GJB2) gene in Indonesian patients by using the PCR-RFLP (Polymerase Chain Reaction-Restriction Fragment Length Polymorphism ) analysis. Materials and Methods: Forty patients with prelingual nonsyndromic sensorineural hearing loss in Makassar Indonesia were identified and genomic DNAs were extracted from peripheral leukocyte blood of each subject. The important region for connexon-connexon interaction of GJB2 gene in the exon 2 was amplified by using PCR. RFLP analysis (ApaI enzyme) was performed to detect the 235delC mutation in all subjects. Result: The target fragment (722bp) of exon 2 in 40 subjects of prelingual nonsyndromic sensorineural hearing loss were amplified by using PCR method. No 235delC mutation of connexin 26 (GJB2) gene was identified in our RFLP (ApaI enzyme) analysis. Conclusion: No 235delC of connexin 26 (GJB2) gene mutation was found in our preliminary study in 40 Indonesian patients with prelingual nonsyndromic sensorineural hearing loss.