Genetic Etiology of Sensorineural Hearing Loss in Slovak Auditory Implant Recipients

Background: Hereditary hearing loss is not only the most common form of bilateral sensorineural hearing loss (SNHL) in childhood, but it also plays an important role in adult onset SNHL.

Objective: To better understand the etiology of SNHL and its impact on postoperative functional results in auditory implant recipients.

Methods: To date, 185 out of 430 cochlear implant (CI) recipients from our center underwent genetic testing for SNHL. Moreover, four SNHL patients with other implantable devices (ABI, VSB, EAS) were also included in the study. Of them, 145 (76.7%) suffered from prelingual and 44 (23.3%) from postlingual deafness. Distinct syndromic SNHL was detected in 15 cases (8.1%). DFNB1 locus was routinely analyzed in all subjects. Subsequently, target genetic testing was performed in selected cases based on their clinical picture and few individuals were also involved in our pilot cohort analyzed by next generation sequencing.

Results: We identified exact genetic etiology in 76 (40.2%) subjects. The detection rate was obviously higher in the prelingual group, in which the confirmed genetic causes accounted for 49% of the cases. The most prevalent pathogenic variants were found in GJB2 gene, which was found as causative factor in 66 individuals. Other identified genes included: GJB6, SLC26A4, TMC1, LOXHD1, MYO15A, NF2, WFS1, and tRNALeu.

Conclusions: Molecular-genetic investigation belongs to the key diagnostic tools in evaluation of CI candidates. Known genetic etiology shows higher prevalence in CI recipients than in the general hearing impaired population with bilateral SNHL.

Supported by APVV-15-0067 and VEGA 1/0214/16.