Genetic carrier screening can help detect whether an individual a carrier for various hereditary disorders. When a couple conceives a baby, both the mother and father contribute genetic material to the developing child. A mother can undergo genetic carrier screening to better understand what traits may potentially be passed down to the baby.
In fact, both men and women can choose to be tested, but it is not uncommon for only one parent to have the test. To understand the benefits of carrier screening and how it differs from other genetic tests, it is important to understand how and why these tests are used.
What Carrier Screening Tells Us
Genetic screening can use a simple blood test to look for a wide range of genetic conditions and traits. Genetic testing can help a woman understand her risk for developing breast cancer or better understand her ethnic heritage. However, genetic carrier screening is a unique type of testing that can be very beneficial for expecting parents.
Carrier testing is often recommended to determine whether or not someone has a gene for a genetic disorder that they themselves do not have. This is referred to as being a genetic carrier for a condition. An individual’s carrier status is important for determining whether a future child is at risk for developing a specific genetic condition, and can help to inform a family’s future reproductive decisions.
The Genetics Behind Carrier Status
It is possible to be a genetic carrier for autosomal recessive genetic conditions. An individual generally has two copies of each gene, one from each parent. Sometimes, the information on these genes “mixes” to determine a trait an individual will have. Other times, one of the genes “wins” and the other “loses.” The winning gene is called dominant and the losing gene is called recessive.
In autosomal recessive diseases, the healthy gene is dominant and the disease gene is recessive. If an individual gets a healthy gene from one parent and a disease gene from the other, he or she will not develop the condition because the healthy gene will win.
Cystic fibrosis (CF), sickle cell anemia, and Tay-Sachs disease are all examples of serious autosomal recessive diseases. If an individual gets a gene for any of these disorders from one parent only, he or she won’t develop the disease. However, they will still carry the gene for the disorder, with a risk of passing it on to a child if their partner contributes the same disease gene. Autosomal recessive diseases appear only when someone gets two copies of the gene for the same condition.
Who Needs Genetic Carrier Screening
Generally, the parent who has a higher risk of carrying a gene associated with a specific genetic disorder should get tested for the disorder first. If the test is negative, it may not be necessary for their partner to be tested. However, if the first partner to be tested is positive, meaning they are a genetic carrier, the partner should likely be tested as well. When both parents are carriers of a gene for the same autosomal recessive disease, they have a 25% chance of having a child with the condition. If you are concerned about carrier status for a specific genetic condition, make an appointment with a genetic counselor to further understand carrier status and plan for genetic testing.