Autosomal dominant non-syndromic hearing loss caused by a novel mutation in MYO7A: A case report and review of the literature

Abstract

BACKGROUND

Variants in the MYO7A gene commonly result in Usher syndrome, and in rare cases lead to autosomal dominant non-syndromic deafness (DFNA11). Currently, only nine variants have been reported to be responsible for DFNA11 and their clinical phenotypes are not identical. Here we present a novel variant causing DFNA11 identified in a three-generation Chinese family.

CASE SUMMARY

The proband was a 53-year-old Han male who presented with post-lingual bilateral symmetrical moderate sensorineural hearing loss. We learned from the patient’s medical history collection that multiple family members also had similar hearing loss, generally occurring around the age of 40. Subsequent investigation by high-throughput sequencing identified a novel MYO7A variant. To provide evidence supporting that this variant is responsible for the hearing loss in the studied family, we performed Sanger sequencing on 11 family members and found that the variant co-segregated with the deafness phenotype. In addition, the clinical manifestation of the 11 affected family members was found to be late-onset bilateral slowly progressive hearing loss, inherited in this family in an autosomal dominant manner. None of the affected family members had visual impairment or vestibular symptoms; therefore, we believe that this novel MYO7A variant is responsible for the rare DFNA11 in this family.

CONCLUSION

We report a novel variant leading to DFNA11 which further enriches the collection of MYO7A variants, and our review of the nine previous variants that have been identified to cause DFNA11 provides a reference for clinical genetic counseling.

Keywords: Autosomal dominant hearing loss; MYO7A gene; Non-syndromic hearing loss; Variant; Hereditary hearing loss; Case report

Core Tip: Autosomal dominant non-syndromic hearing loss caused by the MYO7A variant (DFNA11) is rare and characterized by post-lingual sensorineural hearing loss with no or mild vestibular dysfunction. To date, only nine variants have been identified to be responsible for DFNA11. Here we present a novel variant (c.1531G>A) causing DFNA11 identified in a three-generation Chinese family. Progressive hearing loss is the only clinical manifestation in this family, and the onset age of affected members is later and more concentrated than that of other DFNA11 families. Our findings further enrich the collection of MYO7A mutations, and our review of the nine reported DFNA11 families can provide a reference for clinical genetic counseling.