A gene is a part of your body’s cells that stores instructions for the way your body grows and works. Genes come in pairs—you get one of each pair from each parent.
Sometimes the instructions in genes change. This is called a gene change or a mutation. Parents can pass gene changes to their children. Sometimes a gene change can cause a gene to not work correctly. Sometimes it can cause birth defects or other health conditions.
For certain conditions, if you inherit a gene change from just one parent, you have the gene change but not the disease. When this happens, you’re called a carrier. A carrier of a genetic mutation does not have any symptoms of the disease or condition. But, if their partner carries a change in the same gene, then they are at risk to have a baby with the condition.
If you and your partner both carry the gene change for a condition, your baby may get two gene changes (one from each of you) and have the disease. If both you and your partner are carriers (you both have the gene change), there is:
A 1-in-4 chance (25 percent) that your baby can have the disease
A 1-in-4 chance (25 percent) that your baby won’t have the disease and won’t be a carrier
A 1-in-2 chance (50 percent) that your baby won’t have the disease but will be a carrier
Who should get carrier screening?
Carrier screening is simply a blood test. The updated recommendations for carrier screening include:
- All pregnant women should be offered information about carrier screening. They may then choose to have some screening or none at all.
- Ideally, carrier screening should be done before pregnancy.
- If a woman is a carrier for a specific condition, her partner should be offered carrier screening as well.
- If both parents are found to be carriers of a specific disorder, they should meet with a genetic counselor. This will allow them to better understand the condition, the possible risks to their children, and how other family members may be affected.
What conditions should be tested for?
ACOG now recommends ALL WOMEN be offered carrier screening for the following conditions:
- Spinal Muscular Atrophy (SMA): SMA is a disease that attacks nerve cells in the spinal cord. These cells communicate with your muscles. As the neurons die, the muscles weaken. This can affect walking, crawling, breathing, swallowing, and head and neck control.
- Cystic fibrosis (CF): CF is a condition that affects breathing and digestion. It’s caused by very thick mucus that builds up in the body. This thick and sticky mucus builds up in the lungs and digestive system and can cause problems with how you breathe and digest food.
- Hemoglobinopathies: These are blood conditions that are caused by problems with hemoglobin. Hemoglobin is a protein in the blood that carries oxygen. There are different kinds of hemoglobin in the blood, and there are many kinds of hemoglobin disorders. Some are caused when hemoglobin doesn’t form correctly or when your body doesn’t make enough hemoglobin.
Additional carrier screening should be offered for other conditions based on family history. If you are planning a pregnancy or are pregnant already, make sure you talk to your health care provider about the new guidelines and discuss any questions or concerns you may have.
Have questions? Text or email us at AskUs@marchofdimes.org.