Discriminating between inherited and non-inherited sporadic hearing loss is challenging. Here, we attempted to delineate genetic inheritance in simplex cases of severe-to-profound congenital hearing loss in Korean children. Variations in SLC26A4 and GJB2 in 28 children with bilateral severe-to-profound non-syndromic hearing loss (NSHL) without familial history were analyzed using Sanger sequencing. Genetic analysis of individuals without mutations in SLC26A4 and GJB2 was performed by whole exome sequencing (WES). Bi-allelic mutations in SLC26A4 and GJB2 were identified in 12 and 3 subjects, respectively. Of the 13 individuals without mutations in SLC26A4 and GJB2, 2 and 1 carried compound heterozygous mutations in MYO15A and CDH23, respectively. Thus, 64.3% (18/28) of individuals with NSHL were determined to be genetically predisposed. Individuals with sporadic severe-to-profound NSHL were found to mostly exhibit an autosomal recessive inheritance pattern. Novel causative candidate genes for NSHL were identified by analysis of WES data of 10 families without mutations in known causative genes. Bi-allelic mutations predisposing to NSHL were identified in 64.3% of subjects with sporadic severe-to-profound NSHL. Given that several causative genes for NSHL are still unidentified, genetic inheritance of sporadic congenital hearing loss could be more common than that indicated by our results.
Bibliographical noteFunding Information:
This study was provided with bioresources from the National Biobank of Korea, Centers for Disease Control and Prevention, Republic of Korea (4845-301, 4851-302 and -307). This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF), funded by the Ministry of Education (2015R1D1A1A01056685 to H.Y.G.) and by the Korea government (MSIP) (2016R1A2B4007268 to C.J.Y. and 2014R1A2A1A01003385 to Y.J.). We are grateful to Alice Jaewon Lee for the scientific discussion and proofreading the manuscript.
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