Insights into the Pathobiology of TMPRSS3-Related Hearing Loss and Implications for Cochlear Implant Patients with TMPRSS3 Mutations.

Abstract

OBJECTIVES To review the audiological outcomes after cochlear implantation (CI) for TMPRSS3-associated autosomal recessive non-syndromic hearing loss (ARNSHL) and evaluate the spatial expression pattern of TMPRSS3 within the human cochlea. METHODS Review all published cases of CI in patients with TMPRSS3-associated ARNSHL to compare postoperative consonant-nucleus-consonant (CNC) word performance to published adult CI cohorts. Protein structural modeling of TMPRSS3 variants associated with post-lingual hearing loss. Determine TMPRSS3 expression pattern in human inner ear organoids and human cochlea. RESULTS Nine articles detailed 27 patients (30 total CI ears) with TMPRSS3-associated hearing loss treated with CI. Of these, 6 cases reported prelingual onset (< 2yo) and 24 cases reported post-lingual onset (≥2yo) of hearing loss. Subjectively, 85% of cases had a favorable outcome. Objectively, the postoperative mean (SD) post-operative CNC word score was not significantly different than other adults [66.2% (25.8%) correct vs. 50.1% (12.5%); F(1,6) = 1.97, P = 0.21]. In the TMPRSS3 cohort, poor performers (CNC < 30% correct) were significantly older than good performers [49 (± 13.3) years vs. 17.4 (± 18.4) years; P < 0.01] and all harbored the A138E variant. TMPRSS3 immunostaining is restricted to the otic epithelial cells and is not expressed within auditory neurons of human cochlea and human inner ear organoids. CONCLUSIONS Patients with TMPRSS3-related hearing loss exhibit similar postoperative performance to other adult CI patients. TMPRSS3 is not expressed in human auditory neurons and the duration of hearing loss prior to CI likely contributes to poor performance.