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. A genetic test is a blood test that 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 if 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.

Carrier screening is recommended 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.

Pregnant women can have a genetic test using chorionic villus sampling or amniocentesis. And newborns can have a genetic test too.

Genetic counseling is recommended before having a genetic test. For more information, see the topic Genetics or Genetic Test.


  1. American College of Obstetricians and Gynecologists (2005, reaffirmed 2007). Update on carrier screening for cystic fibrosis. ACOG Committee Opinion No. 325. Obstetrics and Gynecology, 106(6): 1465–1468.

Last Updated: June 23, 2009

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