A clinical guidance to DFNA22 drawn from a Korean cohort study with an autosomal dominant deaf population: A retrospective cohort study

Background: The MYO6 gene, if altered, can cause nonsyndromic hearing loss (NSHL) either in an autosomal dominant (AD) (DFNA22) or recessive form. The present study identified MYO6 variants in the cohort of Korean AD NSHL families and investigated the audiological phenotypes of DFNA22 with respect to suggesting clinical guides for the counseling of DFNA22.

Methods: A retrospective cohort study was performed on 81 AD NSHL families in two hospitals. Among them, five families (SH21, SB60, SB247, SB290 and SB305) segregating with MYO6 variant were genetically and clinically assessed.

Results: We identified two novel missense variants of MYO6: p.G223R (SB290) and p.T158R (SB305). A known heterozygous truncation variant, p.R205X, reported previously (SH21, SB60), was identified (SB247). The overall frequency of DFNA22 among such cases was 6.2%. Specifically, we found p.R205X from three of five DFNA22 families (60%). Five DFNA22 families demonstrated extremely diverse audiogram configurations and age of onset with even intrafamilial variations, whereas the severity of hearing loss mostly ranged within moderate.

Conclusions: We report a recurring predominant allele and two new missense variants of MYO6, highlighting the significant contribution of MYO6 to AD NSHL in the Korean population. Extremely diverse audiological configurations of DFNA22 suggest that MYO6 should be considered in future genetic studies of patients with AD NSHL. Gradual progression with a good speech audiometry score could provide physicians with clinical insight with respect to advising patients to use hearing aids or consider middle ear implants, whereas, in the case of certain exceptional circumstances, physicians could provide patients with the option to consider a cochlear implant.