CYSTIC FIBROSIS CARRIER TESTING

Carrier testing for Cystic Fibrosis (CF) is an elective blood test that can be added to the other prenatal blood tests usually done in pregnancy.  CF testing is usually covered by insurance, although this can only be verified by calling your insurance company.

In the Caucasian (white) population, there is approximately a 1 in 3300 chance of having CF. CF is a genetic disorder that causes a life-long illness that is usually diagnosed in the first few years of a child’s life.  The disease causes serious problems with breathing and digestion.  CF does not affect appearance or intelligence.  Some forms of CF are milder or more severe than others, for reasons not well understood.  Prenatal testing will not necessarily predict the severity of the disease, nor are there treatments available for a baby before birth.  Children with CF usually need daily medication to treat their digestive problems, and need daily respiratory therapy to clear excess mucus from their lungs.  These children are especially susceptible to lung infections, which often require antibiotics and hospitalization.  In general, people with CF have a shortened life expectancy.  Some will die in childhood, but some will live into their 40’s or later.  Treatment is costly and time consuming for families.  Although here is presently no cure for CF, research on more effective treatments is underway. 

The purpose of CF carrier testing is to evaluate a couple’s risk for having a child with the disease.  CF occurs only when a child inherits the defective gene that both parents carry.  There is no known health problem associated with being a CF carrier.  An important point to note is that if both parents are carriers of the CF gene, then their baby will have a 1 in 4 (25%) chance of having the disease.  If the results of the initial test show that a pregnant woman carries the gene for CF, then testing would then be recommended for the baby’s father.  If the father’s test is negative, no further testing is necessary.  However, if the results of both tests show that the couple is at high risk for having a baby with CF, genetic counseling will be recommended, and additional testing can be done to determine if the developing baby will have CF.  Most women’s test results are normal.  The purpose of CF testing is to give parents information as soon as possible to prepare them for having a child with special health care needs.

The chances of being a CF carrier vary by race/ethnicity.  The table below outlines the incidence of CF carriers by race.  *Remember, both parents must be carriers for their child to have CF.

If you have a relative with CF or who is a carrier, your chances of being a carrier are greater than the statistics noted in the above table. 

It is possible to have a negative test but still carry an unusual CF gene that prenatal testing cannot identify.  Like most medical tests, CF carrier testing is not perfect, though the chances of having a false negative result are rare.  If you have been tested once and are found to be a carrier, these results will not ever change.  However, if you have a negative test now and become pregnant again in the future, you should discuss testing again with your doctor, as test technology changes and more advanced testing may become available.

You will have an opportunity to discuss this and other prenatal testing with your physician in your upcoming visits to our office.  We encourage you to ask any questions you may have, so that you will feel well informed and that you have made the best decisions possible.

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