It was shown that, in addition to the previously detected CFTR gene mutations, the mutations c.2012delT (2143delT), c.2052_2053insA (2184insA), c.262_263delTT (394delTT), and c.3691delT (3821delT) can also be considered frequent for ethnic Russian CF patients. The gene discussed is CFTR; the disease is cystic fibrosis.