A hereditary disease whose symptoms usually appear shortly after birth. They include faulty digestion, breathing difficulties and respiratory infections due to mucus accumulation, and excessive loss of salt in sweat. In the past, cystic fibrosis was almost always fatal in childhood, but treatment is now so improved that patients commonly live to their 20s and beyond.

Dr. Francis Collins, director of the National Human Genome Research Institute, defines cystic fibrosis.

Related terms: gene, gene therapy, positional cloning, recessive.