[A hereditary hearing loss case accompanied by unilateral sudden hearingloss:GJB2 235delC homozygotes related late-onsetmoderate hearing impairment].

Summary A sporadic,case suffering from sudden hearing loss of left ear accompanied by tinnitus when he visited our hospital in 2015,whose hearing threshold had a fluctuation in recent two year.Mutation screening of GJB2 gene,was carried out on the case and his parents by polymerase chain reaction amplification and Sanger sequencing.Targeted 307 genes capture and next-generation sequencing(NGS) was performed to explore,additional possible genetic codes.GJB2 235delC homozygotes were identified,and NGS showed no other pathogenic,likely pathogenic variations or modifier genes.The overexpression of Connexin30 or the presence of modifier genes may be the possible mechanisms of the late-onset moderate hearing impairment phenotype,and much more cases collection and further in vivo/vitro experiments need to be done to decipher the genetic code.