A Japanese family showing high-frequency hearing loss with KCNQ4 and TECTA mutations.

CONCLUSIONS

We describe a Japanese family with high-frequency sensorineural hearing loss (SNHL) harboring a c.211delC mutation in the KCNQ4 gene. Families showing progressive high-frequency SNHL should be investigated for mutations in the KCNQ4 gene.

OBJECTIVE

To determine the responsible deafness gene in a Japanese family with dominantly inherited high-frequency SNHL of unknown etiology.

METHODS

We performed hearing tests for five members of the family, and the three affected with hearing loss underwent further audiological and vestibular examinations. Genetic analysis was performed to identify any possible causative mutations, as well as analysis of detailed clinical findings to determine the phenotype.

RESULTS

The three affected subjects showed high-frequency SNHL. Extensive audiologic evaluation suggested cochlear involvement and progressive hearing loss. As for bilateral caloric testing, two of the three affected subjects showed hyporeflexia with recurrent vestibular symptoms. We identified the c.211delC mutation in the KCNQ4 gene and the c.2967C>A (p.H989Q) mutation in the TECTA gene. Based on the genotype-phenotype correlation, the c.211delC mutation in the KCNQ4 gene was associated with high-frequency SNHL in this family.