Cystic fibrosis is a genetic disorder that affects the lungs, digestive system, and reproductive system. It causes thick mucus to build up in the lungs, pancreas, and other organs. This leads to frequent lung infections, issues absorbing nutrients, and potential pancreatic destruction. About 30,000 children and adults in the US have cystic fibrosis. Without a family history, the chance of a child having cystic fibrosis is 1 in 2,500. With a family history, the chance increases to 25%.