Abstract
Recent advances in molecular genetic testing (MGT) have improved identification of genetic aetiology of candidates for cochlear implantation (CI). However, whether genetic information increases CI outcome predictability in post-lingual deafness remains unclear. Therefore, we evaluated the outcomes of CI with respect to genetic aetiology and clinical predictors by comparing the data of study subjects; those with an identified genetic aetiology (GD group), and those without identifiable variants (GUD group). First, we identified the genetic aetiology in 21 of 40 subjects and also observed genetic etiologic heterogeneity. The GD group demonstrated significantly greater improvement in speech perception scores over a 1-year period than did the GUD group. Further, inverse correlation between deafness duration and the 1-year improvement in speech perception scores was tighter in the GD group than in the GUD group. The weak correlation between deafness duration and CI outcomes in the GUD group might suggest the pathophysiology underlying GUD already significantly involves the cortex, leading to lesser sensitivity to further cortex issues such as deafness duration. Under our MGT protocol, the correlation between deafness duration and CI outcomes were found to rely on the presence of identifiable genetic aetiology, strongly advocating early CI in individual with proven genetic aetiologies.
Highlights
Recent advances in molecular genetic testing (MGT) have improved identification of genetic aetiology of candidates for cochlear implantation (CI)
Cochlear implantation (CI), which is the surgical insertion of a neuroprosthetic electrode that bypasses the cochlear hair cells and directs sound sensations to the spiral ganglion neurons (SGN), has proven to be effective in auditory rehabilitation practices, such as speech performance, reading skills, and cognitive development of subjects with severe-to-profound sensorineural hearing loss (SNHL)[1]
Forty subjects who underwent MGT were allocated into one of the two following groups, depending on whether we could specify a definitive causative variant among the known deafness genes: the GD group, if a causative variant was identified among the known deafness genes, and the GUD group, if such identification was not possible
Summary
Recent advances in molecular genetic testing (MGT) have improved identification of genetic aetiology of candidates for cochlear implantation (CI). We evaluated the outcomes of CI with respect to genetic aetiology and clinical predictors by comparing the data of study subjects; those with an identified genetic aetiology (GD group), and those without identifiable variants (GUD group). The possibility that central auditory intrinsic deficits coexist with peripheral auditory deficits has been recapitulated by a mouse mutant model lacking both cadherin proteins (i.e. cadherin[23] and cadherin15), since both proteins are required for the development of GABAergic interneurons in the auditory cortex[18] In this regard, identification of pathogenic variants via MGT can be a crucial component in the preoperative evaluation of CI for the prognostic perspectives[15]. Whether genetic information on post-lingual deafness–alone or in conjunction with other clinical factors– contributes to the prediction of CI outcomes may be important to acknowledge to optimize the CI outcomes, given that clinical predictors influence the brain plasticity in post-lingually deafened implantees[8,19]
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