Performance of cochlear implant recipients with GJB2-related deafness

Abstract

Congenital profound hearing loss affects 0.05-0.1% of children and has many causes, some of which are associated with cognitive delay. For prelingually-deafened cochlear implant recipients, the etiology of deafness is usually unknown. Mutations in GJB2 have been established as the most common cause of heritable deafness in the United States. In this report, we identify cochlear implant recipients with GJB2-related deafness and examine the performance of these individuals. Cochlear implant recipients received a battery of perceptive, cognitive, and reading tests. Neither subjects nor examiners knew the etiology of deafness in these individuals. The implant recipients were then examined for mutations in GJB2 using an allele-specific polymerase chain reaction assay, single-strand conformation polymorphism analysis, and direct sequencing. GJB2 mutations were the leading cause of congenital deafness among the cochlear implant recipients screened. Cochlear implant recipients with GJB2-related deafness read within one standard deviation of hearing controls better than other congenitally deaf cochlear implant recipients and non-cochlear implant recipients. Individuals with congenital deafness should be offered GJB2 screening. Positive results establish an etiologic diagnosis and provide prognostic, genetic, and therapeutic information. Effective rehabilitation for profoundly deaf individuals with GJB2-related deafness is possible through cochlear implantation.

Fig. 1

Reading scores of cochlear implant recipients with sufficient follow-up data. Dashed lines mark one standard deviation above and below average for hearing children. Note that the lowest performers have deafness unrelated to GJ7B2-mutations. There is a trend for children with deafness unrelated to GJB2 mutations to be more likely to read greater than one standard deviation below average (P = 0.117).

Fig. 2

Deafness from GJB2-mutations is estimated to account for 20% of prelingual deafness in cochlear implant recipients at the University of Iowa. In general, GJB2-mulations accounted for ~40% of deafness of previously undefined etiology, and ~50% of recessive deafness of undefined etiology.