Cystic fibrosis (CF) is a relatively common recessive genetic disorder that is caused by a mutation in a particular gene. If a person receives an altered gene from one parent and a normal gene from the other parent, he or she will be a CF carrier. Carriers do not have symptoms and are not ill, but they may pass their abnormal copy of the gene on to their children. About 1,000 different CF gene mutations have been identified, but only a few are common. Caucasians from Northern Europe and Ashkenazi Jews have the highest population carrier rates (about 1 in 20-25).

If both parents are CF carriers and pass the altered genes on to their child, then that child will have cystic fibrosis. Patients with CF have thick, sticky mucus in their lungs and pancreas. This can lead to frequent respiratory infections, obstructed pancreatic and liver ducts, and impaired protein digestion. The majority of males with CF are also infertile due to missing or underdeveloped vas deferens, the tubules that transport sperm from the testes. Most people with CF will develop respiratory and pancreatic symptoms very early, although symptom severity will vary from person to person, even in those with the exact same mutation.

Laboratories are now able to perform CF gene mutation testing to check for 25 or more common CF gene mutations. Couples who are planning to become pregnant may want to talk to their doctor and a genetic counselor about this test and other genetic testing. A genetic counselor will be able to provide additional information and help to make an educated decision about the risk of having a child born with Cystic Fibrosis. Those who have an identified CF gene mutation in their family should be tested specifically for that mutation.

Related Pages
Tests: CF Gene Mutation
Conditions: Cystic Fibrosis
Features: The Universe of Genetic Testing
In the News: New DNA Test Approved for Cystic Fibrosis Carrier Screening and Diagnosis