Cystic fibrosis (CF) is a common genetic disorder in the Caucasian population. 
The gene was identified in 1989 on the basis of its map location on chromosome 
7. The encoded gene product, named cystic fibrosis transmembrane conductance 
regulator (CFTR), corresponds to a cAMP-regulated chloride channel found almost 
exclusively in the secretory epithelial cells. Although the major mutation that 
results in a single amino acid deletion (F508) accounts for 70% of the disease 
alleles, more than 550 additional mutant alleles of different forms have been 
detected. Many of these mutations can be divided into five general classes in 
terms of their demonstrated or presumed molecular consequences. In addition, a 
good correlation has been found between CFTR genotype and one of the clinical 
variables--pancreatic function status. An unexpected finding, however, is the 
documentation of CFTR mutations in patients with atypical CF disease 
presentations, including congenital absence of vas deferens and several 
pulmonary diseases. Thus, the implication of CFTR mutation is more profound than 
CF alone.