Posted on: March 30, 2017
Cystic fibrosis (CF) is a genetic disorder that affects approximately 30,000 people in the United States, with about 1,000 new cases discovered annually.
What is Cystic Fibrosis?
CF is a complex disease that causes mucus build-up in organs, such as the lungs and pancreas. Mucus traps bacteria in the lungs leading to infection, difficulty breathing and, eventually, respiratory failure. When mucus builds up in the pancreas, normal digestive enzymes are not released- which limits the body’s ability to absorb nutrients.
Genetics and Cystic Fibrosis
CF is caused when someone inherits two copies of a mutated gene- one from each parent. Individuals with one copy of the mutated gene are considered carriers. There is a 25% chance that two carriers will produce a child with CF. When one parent has CF and the other is a carrier, there is a 50% chance of having a child with cystic fibrosis.
While there are more than 1,500 mutations that can affect the CF gene, not all of them are disease-causing mutations.
Testing for Cystic Fibrosis
Couples planning on getting pregnant may consider undergoing genetic tests to determine if they are a carrier for any of the common disease-causing CF gene mutations. This optional test is up to the couple and can be discussed with your religious leader and fertility specialist before making a decision.
The genetic test requires a sample of your DNA, either from a blood sample or cheek scraping. Current tests look at the most common disease-causing CF gene mutations, but they are not able to identify the rare forms of mutation.
Risks of Carrying a CF Gene Mutation
Individuals of certain races and ethnicities may carry a higher risk of having a disease-causing CF gene mutation. It is most commonly found in Caucasians, with about 1 in 29 Caucasion-Americans being a carrier. Hispanic-Americans have the second highest risk, followed by African-Americans and Asian-Americans, respectively.
If you have a family member who has been diagnosed with cystic fibrosis, there is a higher likelihood you could carry the gene mutation. Talk to your fertility specialist to determine your risk factors and learn more about genetic testing.
Accuracy of CF Genetic Tests
A positive result showing a CF gene mutation is nearly 99% accurate. However, negative results are less accurate. There are many rarer gene mutations not tested for that could exist.
In addition, if you were tested a few years ago to determine whether or not you carry the CF gene mutation, it may be beneficial to be tested again. Previous CF genetic tests had a standard of checking for 32 mutations, while newer tests include 97 possible gene mutations. Ask your fertility specialist if think you may need to be re-screened.