Cystic fibrosis is a genetic disorder that often affects multiple organ systems of the body. Cystic fibrosis is characterized by abnormalities affecting certain glands (exocrine) of the body especially those that produce mucus. Saliva and sweat glands may also be affected. Exocrine glands secrete substances through ducts, either internally (e.g., glands in the lungs) or externally (e.g., sweat glands). In cystic fibrosis, these secretions become abnormally thick and can clog up vital areas of the body causing inflammation, obstruction and infection. The symptoms of cystic fibrosis can vary greatly in number and severity from one individual to another. Common symptoms include breathing (respiratory) abnormalities including a persistent cough, shortness of breath and lung infections; obstruction of the pancreas, which prevents digestive enzymes from reaching the intestines to help break down food and may result in poor growth and poor nutrition; and obstruction of the intestines. Cystic fibrosis is slowly progressive and often causes chronic lung damage, which eventually results in life-threatening complications. Because of improved treatments and new treatment options, the outlook and overall quality of life of individuals with cystic fibrosis has improved and over 50 percent of individuals with the disorder are adults. Cystic fibrosis is caused by mutations to the cystic fibrosis transmembrane conductance regulator (CFTR) gene and is inherited as an autosomal recessive trait.