Genetic mapping and pedigree analysis of non-syndromic congenital deafness in Surabaya, Indonesia

Abstract

Background: Genetic mutations cause 50-75% of congenital deafness. Congenital deafness is a disease divided into syndromic and non-syndromic types. Type B special schools facilitate children with deafness in Surabaya. This study aimed to identify a mutation gene that causes non-syndromic hearing impairment in school students. Methods: This research was an analytic observational study using a cross-sectional method applying simple random sampling of non-syndromic deaf children. The applied tests were pure tone audiometry, polymerase chain reaction (PCR), and hybridization tests. Subjects were evaluated on the pedigree route and then analyzed. Results: A total of 138 participants with non-syndromic hearing loss were enrolled in this study and 49 patients met the inclusion criteria. The subject’s average age was 16.16 years, with more male subjects than female.  The hybridization results obtained six genetic mutations, one subject with mtDNA 1555, one subject with GJB2-299, two subjects with SLC26A4-IVS(7)2, and 3 subjects with unknown mutations. In pedigree analysis, the same genetic mutation was found in two generations of subjects with mtDNA 1555 and GJB2-299 mutations, and mutations of more than one genetic type were found in two generations of subjects with the SLC26A4-IVS(7)2 mutation. Conclusions: This study obtained six genetic mutations in non-syndromic congenital deaf children. Non-syndromic congenital deafness in Indonesia was found to have genetic mutations as a health risk. The risk was heredity with diverse inheritance patterns.