Cystic Fibrosis Cystic fibrosis is an inherited trait that causes mucus and sweat glands to work improperly. It is a lifelong disease.
Cystic fibrosis is the most common fatal genetic disease among white children.
It is less common among other racial groups. A parent may be a carrier of the trait without being affected. Children with cystic fibrosis have a defect in a protein that helps to transport salt across cells. The defective protein allows too much salt to leave the body through sweat. Very low salt levels in the body can cause heartbeat problems or shock.