A KCNQ4 Gene Variant (c.701A > G; p.His234Arg) in a Chinese Family With Nonsyndromic Deafness 2A.

Background: KCNQ4 is a common genetic cause of nonsyndromic autosomal dominant hearing loss. We have identified the family in China with a KCNQ4 (c.701A>G; p.His234Arg) missense variation. In this study, a survey and analysis were performed to investigate the audiological and genetic characteristics of the Chinese family.

Methods: The medical history of family members was collected, and the family members underwent pure tone audiometry, acoustic immittance, and physical examination. The proband was additionally examined by ABR (auditory brainstem response) and DPOAE (distortion product otoacoustic emission). DNA samples from family members were collected, and the possible causative gene of the proband was detected by whole-exome sequencing (WES), which was verified by Sanger sequencing in family members.

Results: The inheritance pattern of the family was an autosomal dominant nonsyndromic type. The hearing loss was characterized by postlingual deafness, high-frequency hearing loss in the early stage, gradually involving the full frequency. About 32-40 years of age, the hearing gradually became stable, the decline rate slowed down, and the final degree of hearing loss was severe. WES results showed that the KCNQ4 gene had a missense variation (c.701A>G; p.His234Arg).

Conclusion: This family has autosomal dominant nonsyndromic hereditary hearing loss caused by a variation in the KCNQ4 gene, characterized by high-frequency hearing loss.