Clinical implications of cystic fibrosis transmembrane conductance regulator mutations.

Cystic fibrosis (CF) phenotypes are determined by mutations in the CF gene, genetic background, and environment. The nature of the cystic fibrosis transmembrane conductance regulator (CFTR) mutation determines the extent of protein function. CFTR mutations that abolish protein function are associated with severe CF phenotypes. Mutants that retain partial function of CFTR are associated with mild phenotypes. The effect of CFTR dysfunction is variable in different tissues. Atypical phenotypes caused by mutations in the CF gene may be revealed by CFTR mutation analysis and family studies. These phenotypes help to define the spectrum of clinical manifestations caused by CFTR mutations.