OTOG was identified as a nonsyndrmoic hearing loss gene in 2012 in two families with nonprogressive mild-to-moderate hearing loss. However, no further literature have this gene for nonsyndromic hearing loss. Furthermore, it is still unclear whether vestibular impairment is involved or not in patients with mutations in OTOG. This study presents a validated second report for homozygous causative mutations in OTOG of mild hearing loss. Whole exome sequencing (WES) was performed in a five-year-old male proband with mild hearing loss. The analysis of WES revealed a homozygous truncating mutation (c.330C > G; p.Tyr110*) in OTOG. The identified novel mutation, p.Tyr110*, leads to a null allele based on the fact that early truncated protein contains no functional domain of otogelin. While defects in otogelin previously reported to result in hearing loss and vestibular dysfunction, p.Tyr110* only caused nonsydromic and nonprogressive hearing loss without any vestibular impairment, indicating that vestibular phenotype would be variable. Given that mild hearing loss is not easy to be detected early, mutations of OTOG may be more prevalent than reported. Therefore, genetic evaluation for OTOG should be considered in children with mild hearing loss with/without vestibular dysfunction.
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 Ministry of Health & Welfare, Republic of Korea ( HI16C0142 to J.J.).
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