A Deletion Involving the Connexin 30 Gene in Nonsyndromic Hearing Impairment

Background Inherited hearing impairment affects about 1 in 2000 newborns. Up to 50 percent of all patients with autosomal recessive nonsyndromic prelingual deafness in different populations have mutations in the gene encoding the gap-junction protein connexin 26 (GJB2) at locus DFNB1 on chromosome 13q12. However, a large fraction (10 to 42 percent) of patients with GJB2 mutations have only one mutant allele; the accompanying mutation has not been identified. DFNB1-linked familial cases with no mutation in GJB2 have also been reported. Methods We evaluated 33 unrelated probands with nonsyndromic prelingual deafness who had only one GJB2 mutant allele. Nine subjects had evidence of linkage to DFNB1. We used haplotype analysis for markers on 13q12 to search for mutations other than the one involving GJB2. Results We identified a 342-kb deletion in the gene encoding connexin 30 (GJB6), a protein that is reported to be expressed with connexin 26 in the inner ear. The deletion extended distally to GJB2, which r...