Novel Mutations in GRXCR1 at DFNB25 Lead to Progressive Hearing Loss and Dizziness

Abstract

Objective: We identified 2 patients in 1 family who had novel mutations in GRXCR1, which caused progressive hearing loss. Methods: One thousand one hundred twenty Japanese hearing loss patients with sensorineural hearing loss from unrelated families were enrolled in this study. Targeted genomic enrichment with massively parallel sequencing of all known nonsyndromic hearing loss genes was used to identify the genetic causes of hearing loss. Results: In this study, 2 affected individuals with compound heterozygous mutations—c.439C>T (p.R147C) and c.784C>T (p.R262X)—in GRXCR1 were identified. The proband had moderate to severe hearing loss and suffered from dizziness with bilateral canal paralysis. Conclusion: Our cases are the first identified in the Japanese population and are consistent with previously reported cases. The frequency of mutations in GRXCR1 seems to be extremely rare. This study underscores the importance of using comprehensive genetic testing for hearing loss. Furthermore, longitudinal audiologic assessment and precise vestibular testing are necessary for a better understanding of the mechanisms of hearing loss and vestibular dysfunction caused by GRXCR1 mutations.