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.

CF is a potentially life-threatening condition in which your 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 are more likely to get 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 intestine. For this reason, people with CF often have trouble digesting food and absorbing nutrients properly. Symptoms in children can also include a swollen abdomen, 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 birth defects. 

What do my child's test results mean?

Many things may affect your child's lab test results. These include the method each lab uses to do the test. Even if your child's test results are different from the normal value, your child may not have a problem. To learn what the results mean for your child, talk with your child's health care provider.

Typically, people do not have the genetic mutations that lead to CF. A child must inherit one copy of a mutant CF gene from each parent to have CF. That is, he or she must have two copies of the defective gene. Some people may have just one copy of one mutation inherited from a parent, making them carriers without having the disease.

Most states now screen all newborns for CF, among other diseases. Different states check for different mutations in children if earlier testing raises a concern. These genetic tests can look for as many as 70 mutations responsible for more than 90 percent of CF cases.  

How is this test done?

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

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.