Cystic fibrosis (CF) is a life-threatening, genetic disease that primarily affects the lungs and digestive system. It is found in about 30,000 people in the United States (70,000 worldwide). People with CF inherit a defective gene that causes a buildup of thick mucus in the lungs, pancreas and other organs.
When mucus clogs the lungs, it can become very difficult to breathe. The thick mucus also traps bacteria in the airways, which can result in infections and inflammation and often leads to severe lung damage, and eventually, respiratory failure. Respiratory problems are the most serious and persistent complication for people with CF.
In the pancreas, the buildup of mucus prevents the release of digestive enzymes that help the body break down food and absorb important nutrients. People with CF often have malnutrition and poor growth.
Cystic fibrosis is a genetic disease. People inherit CF from their parents through genes, which also determine many other characteristics, including height, hair color and eye color.
CF is caused by mutations in a gene that produces a protein, called CFTR. The CFTR protein controls the flow of salt and water in and out of the cells of organs like the lungs and pancreas.
To have cystic fibrosis, a person must inherit two copies of the defective CF gene — one copy from each parent. Both parents must have at least one copy of the defective gene.
People with only one copy of the defective CF gene are called carriers, but they do not have the disease themselves. Each time two CF carriers have a child, the chances are:
- 25 percent (1 in 4) the child will have CF
- 50 percent (1 in 2) the child will be a carrier but will not have CF
- 25 percent (1 in 4) the child will not be a carrier and will not have CF
There are more than 1,800 known mutations of the CF gene. Because there are so many, most genetic tests only screen for the most common mutations.
About 30,000 children and adults in the United States (70,000 worldwide) have CF. An additional 10 million people — about one in every 31 Americans — are symptomless carriers of the defective CF gene. CF is most common in white people, but is found in people of all races and many ethnicities.
Please visit CFF.org to learn more about carrier testing.