목적: The purpose of this study is to elucidate the audiological characteristics of the patients harboring COQ6 variants and to explore the effects of CoQ10 replacement therapy on hearing progression. 방법:We reviewed the in-house database of sensorineural hearing loss (SNHL) and nephrotic syndrome (NS) at Seoul National University Hospital. We analyzed the audiological profiles, including progression of hearing loss, before and after COQ10 supplementation. Patients were subject to start CoQ10 replacement therapy immediately after genetic ascertainment. Specifically, in cochlear implantees, auditory performance was assessed at up to five-time points throughout the 1-year follow-up period. 결과:A total of 10 patients with biallelic COQ6 variants were enrolled in this study. The onset of NS and SNHL were 1.9 years (range 0.8-3.9 years) and 4.1 years (range 1.2-6.3 years), respectively. Of them, 9 (90.0%) progressed to end-stage renal disease (ESRD) and underwent kidney transplantation, even in cases who administered CoQ10 replacement in the early stage. Meanwhile, among 13 ears with residual hearing, the hearing was markedly preserved in 8 ears (61.5%) following CoQ10 supplementation, throughout the follow-up period (range 1.4-4.4 years). In this study, four patients (7 ears, 35.0%) underwent cochlear implantation and significantly improved auditory performance just in 3 months postoperatively. 결론:Taken together, COQ6 variants-induced mitochondrial cytopathies are associated with progressive SNHL and ESRD. Our data suggest that an early genetic confirmation of COQ6 variants is essential in individuals presenting phenotypic combination of NS and SNHL since earlier CoQ10 supplementation may be more effectively prevent progression of hearing loss. Nevertheless, a subset of patients may occur severe deterioration of hearing loss despite CoQ10 supplementation, thus necessitating regular evaluation and timely intervention to retain auditory performance.