GJB2 and sensorineural hearing loss disorder: Moreover, the detected GJB2 mutation from five subjects in group I were not found to contribute to their SNHL, and thus the slightly higher rate of GJB2 single heterozygotes in groups I + III compared with that of controls (4.38% vs 2.58%) suggests that at least some of the monoallelic GJB2 mutations in group III contribute to SNHL.