It is also possible that there was greater recruitment bias toward a higher prevalence of CHARGE syndrome (n = 7) and incomplete partition type III (n = 5) with highly penetrant marker of CHD7 and POU3F4 mutations, in our CI cohort than in the Japanese cohort, as many deaf subjects with such severe inner anomaly in Korea tend to visit our tertiary referral center. Here, CHD7 is linked to CHARGE syndrome.