The Cystic Fibrosis Research program supports both basic and clinical studies on the etiology, molecular pathogenesis, pathophysiology, diagnosis, and treatment of cystic fibrosis and its complications. These studies examine the characterization of the cystic fibrosis gene, its mutations, and the molecular mechanisms by which mutations cause dysfunction in the cystic fibrosis transmembrane conductance regulator (CFTR) protein. Also included are studies aimed at the elucidation of electrolyte transport pathways in affected epithelia, their relationship to the CFTR, and research on the potential roles of CFTR in the transport of molecules in critical cellular processes. The ultimate goal of these mechanistic studies is to develop therapies that modulate the transport defect and improve the functioning of mutant CFTR. Other research is conducted to determine the relationship between genotype and phenotype (e.g., variable clinical presentations and severity of disease) and to delineate the mechanisms underlying the disease’s characteristic inflammation and infection, with the ultimate goal of developing safe and effective methods of therapy for individuals with cystic fibrosis.