Causes
Cystic fibrosis is a genetic disease. That means people inherit it from their parents through genes (or DNA), which also determine a lot of other characteristics, including height, hair color and eye color. Genes, found in the nucleus of all the body’s cells, control cell function by serving as the blueprint for the production of proteins.
To have cystic fibrosis, a person must inherit two copies of the defective CF gene — one copy from each parent. If both parents are carriers of the CF gene (i.e., they each have one copy of the defective gene), their child will have a 25% chance of inheriting both defective copies and having cystic fibrosis, a 50% chance of inheriting one defective copy and being a carrier, and a 25% chance of not having CF or carrying the gene.
Approximately 30,000 people in the United States have cystic fibrosis. An additional 10 million more — or about one in every 31 Americans — are carriers of the defective CF gene, but do not have the disease. The disease is most common in Caucasians, but it can affect all races.



