Newborn Screening

 

Newborn screening for CF is a nationwide program to identify babies born with cystic fibrosis. This was started in Michigan in October of 2007.  Newborn screen lets us avoid what used to be a 15 month delay between the onset of symptoms and the diagnosis of CF.  Newborn screening improves growth and nutritional problems in childhood and reduces mortality from CF.  

 

CF causes a variety of problems but most notably lung and digestive problems. A list of all the manifestations of CF can be found in the image on this page.  This is because the CF gene affects how salt moves through the cells.  Many of these symptoms can be caused by things other than CF.   For a person to have CF they usually need to have two CF gene mutations. There are over 2000 known CF causing mutations. If the sweat test is negative, then there is almost no chance that your baby has CF. 

 

A person has cystic fibrosis when both of the CF genes have mutations. This is because the person inherited one CF gene mutation from each parent. When a mother and father are both CF carriers, each pregnancy has a 1 in 4 (or 25%) chance for the baby to have cystic fibrosis.  The parents of a child with CF are almost always carriers because the rate of new mutations is very low. 

 

 

The CF screening test checks for IRT (Immune Reactive Trypsinogen), which is normally found in small amounts in the body. 

 

When the pancreas is stressed before a baby is born, more IRT is released into the baby's blood. The IRT level can be high for several reasons, including a premature or stressful delivery, or for other reasons. IRT levels also tend to be high in people who have CF. When high IRT levels are detected in the blood, the results of the newborn screening are said to be positive.  

 

In Michigan when the IRT is elevated a 60 mutation panel for CF causing mutations is done.  If two mutations are found the child likely has CF, but this must be confirmed with a sweat test and may depend on the type of mutation.  If one mutation is found the child may be a CF carrier or have CF.  There are over 2000 mutations that can cause CF so it remains possible they may have one of the mutations that was not tested for.  This is why if any mutations are found the infant is referred to a CF Center for sweat testing and genetic counseling.  The sweat test will measure how much salt is in your baby's sweat. This test is the only way to diagnose CF, although other forms of testing can help confirm or inform the diagnosis if the sweat test results are inconclusive. 

 

The Michigan State University Cystic Fibrosis Center uses the testing protocol recommended by the Cystic Fibrosis Foundation to determine if a child with an abnormal newborn screen is a carrier or truly has CF.  A copy of our protocol can be found on this page.  As you can see, the process of making a definite diagnosis can be complicated.  We want to make sure we can get to a correct diagnosis as quickly as possible every time.  

 

Carriers rarely have any problems related to their CF mutation.  The most important thing to do is make sure they know they are carriers and meet with a genetic counselor prior to having children of their own so they know the risks and their partner can be offered testing. Also monitor for frequent respiratory infections like pneumonia, growth problems, pancreatitis or infertility issues that might be signs of a CF related issues.  This is very rare but not impossible as sweat chloride levels can change over time and false negative sweat tests, though rare, are possible.  

 

This will be discussed in great detail at your first appointment after the sweat test.  We have a multidisciplinary team that focuses on every aspect of care a person with CF may need.  We will follow your child very carefully monthly at first and then at least 4 times a year afterwards to make sure we are doing everything we can to keep your child healthy and thriving.  The prognosis for children with CF is improving every year and we currently expect most children born with CF to have normal lung function well into adulthood.

 

Genetic testing can tell whether you, your partner or both of you are CF carriers like your baby. A genetic counselor can help you learn more about CF carrier testing and arrange for you to be tested. Ask your health care provider to help you find a genetic counselor and to order the CF carrier testing for you and your partner. Any blood relative (brother, sister, aunt, uncle, cousin, etc.) of a CF carrier might also be a CF carrier. Keep in mind that just because your baby is a carrier does not mean both parents can not be carriers.  If your child is a carrier and you have not had carrier testing you are technically at increased risk of having a child with CF.  Learning that you or your child is a CF carrier may be helpful for other family members in deciding whether or not to have testing to find out if they too carry a CF gene mutation.

 

To learn more about testing for cystic fibrosis and Newborn Screening for CF, visit the CF Foundation’s Web

site (www.cff.org).

 

Having a child’s newborn screen be positive can be stressful.  If you would like to talk to someone or would like a referral for stress or anxiety related to this please let us know and we can provide assistance. 

 

If you have questions or concerns that can not wait for your sweat test and appointment please call 517-884-8600 and ask for our CF Coordinator.  Our team is here to help you through this stressful time.