GJB2 and deafness: The carrier frequencies of deafness-causing GJB2 mutations in our case group were 0.30% for c.35delG, 2.28% for c.109G > A, 3.19% for c.176del16, 15.50% for c.235delC, 4.71% for c.299delAT, 0.30% for c.504insGCAA, 0.30% for c.605ins46 and 0.30% for c.608TC > AA, respectively.