HEARRING group genetic marker study: genetic background of CI patients.

Background: While cochlear implantation (CI) and electric acoustic stimulation (EAS) have a positive outcome in most cases, their effectiveness varies depending on the etiology of the hearing loss. Among the various etiologies, genetic factors are the leading cause of hearing loss and may impact CI and EAS outcomes.

Aims/objectives: To reveal the genetic background of the hearing loss in CI/EAS patients in each ethnic population, we undertook a multi-center study involving the genetic testing of hearing loss in CI/EAS patients from 10 centers.

Material and methods: Saliva samples and clinical information for the patients and their family members were obtained and next-generation sequencing analysis using a panel carrying 63 deafness genes was then performed.

Results: Genetic testing successfully identified the causative gene variants in 54.5% (48/88) of patients with pre-lingual onset hearing loss (onset under 6 years) and in 12% (12/95) of those with late-onset hearing loss (onset at 6 years or more).

Conclusions and significance: We clearly indicated that genetic factors are the most common cause of hearing loss regardless of ethnic background. Saliva-based genetic testing is a useful tool for multi-center studies seeking to clarify the genetic causes of hearing loss in CI or EAS patients between countries separated by distance.