Mutations in the GJB2 gene (connexin 26) are the most common cause of nonsyndromic autosomal recessive sensorineural hearing loss. Genetic testing of GJB2 may offer opportunities to predict the features of hearing loss and prognostication of speech-language development in children with hearing loss. The present study assessed the clinical features of hearing and some aspects of language development in congenital deafness due either to GJB2 mutations or to other factors in Japanese patients who had been habilitated with hearing aids. Thirty-five unrelated subjects with nonsyndromic, congenital, bilateral sensorineural hearing loss were enrolled in the study. Among them, 16 had biallelic GJB2 mutations related to hearing loss and 17 lacked such mutations. As has been reported in populations of European ancestry, the present Japanese subjects with GJB2 mutations had a relatively high incidence of the flat pattern audiogram and nonprogressive pure tone thresholds compared with subjects without GJB2 mutations. Subjects with GJB2 mutations and those without GJB2 mutations both showed a similar tendency in speech perception, some aspects of language development, and communication methods. In both groups, development of reading ability tended to be normal, but vocabulary development tended to be delayed. The present results establish the basis for future studies to aid in the evaluation and follow-up of patients with congenital hearing loss associated with GJB2 mutations who are habilitated with hearing aids.
Copyright 2006 S. Karger AG, Basel.