Audiological Features in Patients with GJB2 c.235delC Homozygous Mutations

GUO Chang; JIANG Yi; HUANG Shasha; KANG Dongyang; ZHANG Xin; YANG Suyan; JIANG Yuanshi; DAI Pu

doi:10.3969/j.issn.1672-2922.2018.02.008

Abstract：Objective The present study aims to characterize the audiological profile in patients with GJB2 c.235delC homozygous mutations,and specifically,the symmetry of bilateral hearing in each individual.Methods A to-tal of 100 cases of GJB2 c.235delC homozygous mutations with NSHL diagnosed at the Chinese PLA General Hospital between 2007 and 2014 were analyzed in this study.Genetic tests,pure tone audiometry,and multiple-frequency audito-ry steady-state evoked responses(ASSR)tests were performed. Results Most of the cases presented with substantial hearing impairments.Hearing loss was profound in 51 cases,severe in 20 cases,and moderate to severe in 21 cases.De-scending (37%) and flat (21%) audiogram types were common. Sixty-one out of the 100 cases showed asymmetrical hearing loss,of which 36 demonstrated audiogram curve asymmetry(Type A asymmetry)including unilateral residual hearing or total hearing loss in 11 cases(Type Aa),18 showed paralleled interaural differences(Type B asymmetry), and the remaining 7 showed irregular interaural differences(Type C asymmetry).In patients with asymmetric hearing, hearing loss was profound in 21 cases(34.4%),severe in 17 cases(27.9%),and moderate-to-severe in 17 cases(27.9%), with the descending (36.1%) and flat (23.0%) patterns being most common. In contrast, among the patients showing symmetric hearing, most (30 cases, 76.9%) presented with severe hearing loss with descending (38.5%) or residual (30.8%)types of audiogram.Conclusions Patients with GJB2 c.235delC homozygous mutations-related hearing impair-ment demonstrate diverse phenotypes of hearing loss,with a substantial number of cases showing asymmetric hearing.