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.

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