Management of pulmonary disease in patients with cystic fibrosis.

Cystic fibrosis is the most common life-shortening autosomal recessive disorder in the white population, affecting approximately 30,000 persons in the United States.1 It is caused by mutations in a single gene on the long arm of chromosome 7 that encodes the cystic fibrosis transmembrane conductance regulator (CFTR) (Figure 1).2 CFTR has multiple functions involving fluid balance across epithelial cells. It acts as a chloride channel activated by cyclic adenosine monophosphate (cAMP)3 and may stimulate other chloride channels4 and inhibit sodium absorption by epithelial sodium channels.5 Mutations in the CFTR gene result in defective chloride transport in the epithelial cells in . . .