Cystic fibrosis (CF) is an inherited disease of your mucus and sweat glands. It affects mostly your lungs, pancreas, liver, intestines, sinuses, and sex organs.About 30,000 people in the United States have cystic fibrosis (CF). Detection of 31 CF mutations � this assay detects as many as 90% of all the mutations that cause cystic fibrosis. Within specific ethnic groups there may be higher or lower detection efficiency.