What Causes CF?

Cystic fibrosis (CF) is a genetic disorder. A child must inherit two defective CF genes (one defective gene from each parent) to have the disease.

A person who has inherited only one defective CF gene is a carrier of CF and does not have the disease but can pass it on to his or her children. This person can also pass on carrier status.

• If only one parent is a carrier of a defective CF gene, the child will not have CF. But there is a 50% (1-in-2) chance that the child will be a CF carrier.
• If both parents are carriers, there is a 25% (1-in-4) chance that the child will have CF, and a 50% chance that the child will be a carrier.

What Is Carrier Screening?

Cystic fibrosis (CF) carrier screening is a blood test that determines if you are a carrier of the defective gene that causes CF. The test can help you determine if you and your partner have an increased chance of having a child born with CF.

Who Should Be Screened?

Genetic testing can help people find out if they may be carriers of cystic fibrosis (CF). This type of genetic testing allows parents to find out if they have an increased chance of having a child with CF. Anyone who is interested in knowing his or her carrier status can request the test, but the test can only be ordered by a doctor. Genetic counseling to help you understand the meaning and possible results of the test is recommended prior to genetic testing.

CF carrier screening is recommended for:¹

• Adults with a positive family history of CF.
• Partners of people with CF. If one partner has CF and the other partner has the defective CF gene, a child will have a 50% chance of having CF.
• Couples planning to have children.
• Pregnant women (and their partners) who seek prenatal care, regardless of family history.