This significantly reduces the molecular genetic testing loads needed to reach a final genetic diagnosis through GJB2 testing alone.3 Although the proportion of nonsyndromic hearing loss and deafness 1 (DFNB1) among nonsyndromic sporadic or autosomal recessive severe to profound SNHL significantly varies, it still accounts for ∼15% of such subjects in Koreans, making GJB2 and solute carrier family 26, member 4 (SLC26A4) the most frequent causative genes of SNHL.3–7 However, it is not always straightforward to diagnose DFNB1 in subjects carrying GJB2 mutations. This evidence concerns the gene GJB2 and sensorineural hearing loss disorder.