Genetic test for cystic fibrosis

If cystic fibrosis is suspected, a genetic test may be done to confirm the results of an unclear or positive sweat test. This blood test detects changes in the genetic material (DNA) that causes cystic fibrosis.

A genetic test may also be done to screen people who want to know whether they are likely carriers of cystic fibrosis, or what their chances are of having a child who has cystic fibrosis. Anyone who is interested in knowing his or her status can request the test, but a doctor must order it and the test is fairly expensive. Genetic counseling is recommended before having a genetic test.

Some states offer genetic testing for the cystic fibrosis gene. The National Institutes of Health (NIH) recommend testing for:¹

• Adults who have a positive family history of cystic fibrosis. They may be a carrier of the defect in the cystic fibrosis gene.
• Partners of people who have cystic fibrosis. If the partner also has the defective cystic fibrosis gene, a child will have a 50% (1 in 2) chance of having cystic fibrosis.
• Couples who are currently planning to become pregnant.
• Pregnant women (and their partners) who seek prenatal care, regardless of family history.

A genetic test for cystic fibrosis also can be done before birth using chorionic villus sampling (CVS) or amniocentesis.

Citations

1. Genetic Testing for Cystic Fibrosis. NIH Consensus Statement, vol. 15, no. 4 (1997 April 14–16).