Even when there is no family history of the disorder, the American College of Gynecologists recommends that all couples planning a pregnancy or having their first visit for prenatal care be offered a
carrier screening test for
cystic fibrosis (CF). Health care providers are more likely to offer the test to those considered at risk, notes the March of Dimes. CF testing is now also recommended for all newborns, and many states include a CF test in their newborn screening panel [See
Newborn Screening for more information]. Laboratories use
CF gene mutation testing to check for 25 or more common CF gene mutations. Those who have an identified CF gene mutation in their family should be tested specifically for that mutation.
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 to 25).
If both parents are carriers and both pass the altered genes on to their child (a possibility that is fairly uncommon), then that child will have CF. Those with the disorder 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 develop respiratory and pancreatic symptoms very early, although symptom severity varies from person to person, even in those with the exact same mutation.
Couples planning a pregnancy can talk to their health care provider and a genetic counselor about this test and other genetic testing. A genetic counselor can provide additional information and help to make an educated decision about the risk of having a child born with CF. If both parents are carriers, the pregnant woman can have amniocentesis or chorionic villus sampling to help diagnose or rule out CF in the fetus.
Links
March of Dimes: Cystic fibrosis
