Gene Mutation for Cystic Fibrosis in Newborns (Blood)

Does this test have other names?

Genetic test for cystic fibrosis

What is this test?

This is a blood test that screens newborn babies for cystic fibrosis (CF), one of the most common genetic diseases in the U.S. Most cases of CF are diagnosed in babies before their first birthday, and often in the newborn period if there is an abnormal newborn screen. 

CF is a potentially life-threatening condition in which glands secrete abnormally thick mucus that harms different systems in your body, including the airways and pancreas. People with CF tend to develop chronic lung disease and lung infections. They may also have persistent coughing, wheezing, and sinus infections.

In people with CF, digestive enzymes from the pancreas also have trouble reaching the small intestine. For this reason, people with CF often have trouble digesting food and absorbing nutrients correctly. Symptoms in children can also include a swollen belly, bad-smelling stools, poor growth, and salty-tasting skin.

Why does my child need this test?

This test is often part of routine newborn screening, although the exact tests vary by state.

What other tests might my child have along with this test?

In newborns, this test is often done along with other tests for possible endocrine, hematologic, or metabolic conditions.

What do my child's test results mean?

Test results may vary depending on your child's age, gender, health history, and other things. Your child's test results may be different depending on the lab used. They may not mean your child has a problem. Ask your healthcare provider what your child's test results mean for them.

For CF to happen, a child must inherit one copy of a nonworking CF gene from each parent. That is, they must have two copies of the nonworking gene. Some people may have just one copy of the nonworking CF gene, making them carriers without having the disease. Carriers can potentially pass the nonworking CF gene to any future offspring.

Every state and the District of Columbia now screen all newborns for CF, among other diseases. Different states check for different changes (mutations) to the CF gene in children if the newborn screening raises a concern. These genetic tests can look for as many as 70 mutations responsible for more than 9 in 10 CF cases.

How is this test done?

This test needs a blood sample. In a newborn, this is done by pricking the child's heel to get a few drops of blood.

Does this test pose any risks?

Taking a blood sample with a needle carries risks that include bleeding, infection, bruising, or feeling dizzy. When the needle pricks the skin, the newborn may feel a slight stinging sensation or pain. Afterward, the site may be slightly sore.

What might affect my child's test results?

Because the test looks at genetic material, your child's actions don't affect the results of this test.

How does my child get ready for this test?

Your child doesn't need to prepare for this test.