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Carrier testing for cystic fibrosis

​​​​​​​​​​​​​​​​​​​​​​​​​​​​​Cystic fibrosis is an inherited disease and life-long condition that affects the lungs and digestive tract. It occurs in approximately 1 in 3900 births.

Cystic fibrosis can cause breathing problems and lung infections. It can also make it difficult to absorb some types of foods, leading to life threatening weight loss in children.

Early and aggressive treatment can help children with cystic fibrosis, but there is currently no cure.

The symptoms of cystic fibrosis vary – they can be mild in some people, but cause a life-threatening illness in others. In general, cystic fibrosis shortens life expectancy.

What causes cystic fibrosis?

Cystic fibrosis is an inherited genetic condition. It is inherited in a recessive manner. That means that both parents must be carriers. Only when both parents are carriers of cystic fibrosis can the disease occur in their children. If both the mother and the father are carriers, there is a 1 in 4 chance for them to have a child with cystic fibrosis.

Could my baby have it even if no one in my family has it?

Yes. Cystic fibrosis is a common condition.

Carriers of the abnormal gene for cystic fibrosis occur in:  

  • 1 in 29 Caucasian Americans
  • 1 in 46 Hispanic Americans
  • 1 in 65 African Americans
  • 1 in 90 Asian

People of other ethnic backgrounds can be carriers, but the chance is less.

Carriers generally have no health problems associated with cystic fibrosis. So, even if no one else in the family has it, there is still a chance the baby could have the condition. Many babies with cystic fibrosis are born into a family with no known family history of the disease.

What are some reasons to consider carrier testing?

For couples that are known to be carriers, other pregnancy options include:

  • Sperm or egg donation
  • Preconceptual genetic testing
  • Adoption

Consider testing before getting pregnant if you want to have the most options available.

For couples who are already pregnant, they might wish to know whether or not their baby will have cystic fibrosis before it is born.

This also provides the option for the couple to consider pregnancy termination or be better prepared for the birth of a child with cystic fibrosis.

How is the test done?

This test requires a small sample of blood taken at our laboratory department. Results are usually ready in 10 to 14 days. Your health care provider will inform you of the results.

How much does cystic fibrosis carrier testing cost?

Testing costs vary. Your insurance company may or may not cover this cost. It is considered a "standard of care" to be offered carrier testing. Please check with your insurance company for coverage information.

How accurate is carrier testing?

The test detects common genetic mutations for cystic fibrosis, but not all of them. Therefore, the risk is not lowered to zero. The test is most accurate for Caucasians.

What if my partner and I are both carriers?

If your test is positive, the next step is to consider testing your partner. If carrier screening finds that both you and your partner are carriers, then your chance of having a child with cystic fibrosis is 1 in 4 for each pregnancy.

Knowing that both parents are cystic fibrosis carriers allows us to offer further prenatal testing, such as amniocentesis (test where some of the fluid around the baby is tested). This test may allow a couple to know before the child is born whether it is affected with cystic fibrosis. However, there are risks associated with prenatal testing that should be discussed with your provider or genetic counselor.

What if I have a family history of cystic fibrosis?

If you have a family history of cystic fibrosis, and you are interested in carrier testing, we strongly recommend that you contact a genetic counselor. There may be better testing available and it's very important to assess each person's family history individually.

If I decide not to have carrier testing, will I find out if my baby has cystic fibrosis?

All newborns in the State of Wisconsin are screened for cystic fibrosis. Most babies with cystic fibrosis currently born in Wisconsin are identified shortly after birth.

Am I required to have cystic fibrosis carrier testing?

No. Cystic fibrosis carrier testing is being made available to you on a voluntary basis. Some reasons people decline testing include:

  • Knowing you are both carriers would not change your plans to try to become pregnant
  • If you are both carriers, you would not consider pregnancy termination if prenatal testing determined that the baby would have cystic fibrosis
  • If you are both carriers, you would prefer to avoid the risks of prenatal testing and wait until birth to find out if the baby will have cystic fibrosis