A very serious, inherited disease, most often seen in people of northern European descent. The problem is a missing or defective enzyme that regulates sodium levels in secretions. Patients with cystic fibrosis have very thick secretions in their lungs and other organs and do not absorb nutrients normally from their intestine. The pancreas, lungs, sinuses, and reproductive organs are all affected. The degree of organ and glandular involvement varies, with consequent variations in the clinical picture. This is an autosomal recessive disease: it takes a gene from both the mother and the father to produce cystic fibrosis. About 1 in 20 Caucasians are carriers of the defective gene. Cystic fibrosis is much rarer in African-Americans and even rarer in those of Asian descent.