Cystic fibrosis is a genetic disorder that affects the respiratory and digestive systems. People with cystic fibrosis inherit a defective gene on chromosome 7 called CFTR (cystic fibrosis transmembrane conductance regulator). The protein produced by this gene normally helps salt (sodium chloride) move in and out of cells. If the protein doesn’t work correctly, that movement is blocked and an abnormally thick sticky mucus is produced on the outside of the cell. The cells most seriously affected by this are the lung cells. This mucus clogs the airways in the lungs, and increases the risk of infection by bacteria.
The most common mutation almost in 70% of cystic fibrosis patients is a three-base pair deletion in the DNA sequence of CFTR, which causing an absence of a single amino acid in this protein. About 2,500 babies are born with cystic fibrosis in the U.S. each year, and more than 10 million Americans are carriers of this disorder.