Genetic test for cystic fibrosis

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 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 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 properly. Symptoms in children can also include a swollen belly, bad-smelling stools, poor growth, and salty-tasting skin.

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

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

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

For CF to happen, a child must inherit one abnormal copy of the CF gene from each parent. That is, he or she must have two copies of the defective gene. Some people may have just one abnormal copy of the CF gene, 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 the newborn screening raises a concern. These genetic tests can look for as many as 70 mutations responsible for more than 90% of CF cases.

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

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

Your child doesn't need to prepare for this test. Be sure your healthcare provider knows about all medicines, herbs, vitamins, and supplements your child is taking.