목적: GJB2 alleles containing two cis mutations have been rarely found in non-syndromic hearing loss (NSHL). The severity of hearing loss due to GJB2 is extremely variable and sometimes cannot be predicted. Here, we present a Korean patient with NSHL caused by the cis R75Q mutation with V37I and suggest the pathologic mechanism whereby residual hearing is able to be sustained in the cis-mutation. 방법:The propositus who was diagnosed with NSHL at the age 4 and his families were evaluated by pure-tone audiogram and temporal bone CT scan. All the coding exons and intron of GJB2 were sequenced by Sangers method. To identify whether the mutations of GJB2 were cis- or trans-strand, single strand DNA PCR was performed. Biochemical coupling and Hemichannel permeability assays were performed after molecular cloning and transfection of HEK293T cells. Finally, Computational modeling of those mutant GJB2 was analyzed. Students t-tests or analysis of variance followed by Tukeys multiple comparison test was used as statistical analysis. 결과:The patient and his father with the mutations had more residual hearing compared to patients with the dominant mutation alone. Although the difference in hemichannel activity between R75Q alone and R75Q in combination with V37I failed to reach significance, it is of note that there is a possibility that V37I located upstream of R75Q might have the ability to ameliorate R75Q expression. Further, structural analyses revealed that V37I could impact the structure of Cx26-R75Q computational 3D modeling, indicating that cis-mutations of GJB2 can change the thertiary structure interactively. 결론:The R75Q mutation of GJB2 can be ameliorated by the cis-V37I mutation by the change of hemichannel activity of connexin26 and the related structural change.