The aims of the present study were (1) to determine the prevalence and types of GJB2 mutations in a cohort of patients with hearing impairments from the Moravian-Silesian population in the Czech Republic; and (2) to determine the prevalence of mutations in seven additional genes, SERPINB6, TMIE, ESPN, COCH, ACTG1, KCNQ4, and GJB3, which we selected because they were small in size and amenable to screening. The gene discussed is KCNQ4; the disease is hearing loss disorder.