GJB2 and hearing loss disorder: We found significantly more biallelic GJB2 mutations in the early prelingual onset group compared to the late childhood onset group (p = 0.001); in the severe hearing loss group compared to the mild (p = 0.004) and moderate (p = 0.046) hearing loss groups; and in the profound hearing loss group compared to the mild hearing loss group (p = 0.0497).