Learning the basics from a genetic counselor

Hi there,

As a genetic counselor, and a mother, I know that all the new information that comes with pre-pregnancy can be overwhelming. That’s why I wanted to take this opportunity to speak to Ovia families about carrier status testing, and what you need to know to give this kind of test proper consideration prior to getting pregnant.

If you haven’t already heard about carrier status testing, this type of testing allows individuals who are trying to conceive to learn about certain genetically inherited conditions that could potentially impact their children. Here are answers to some of the most frequently asked questions:

“What can I learn from genetic testing?”

Carrier status tests are used to find out if you are a “carrier” for a genetic change — or mutation. Individuals who are carriers typically do not have the genetic condition(s) in question, so they are unlikely to know that they carry a mutation. If you are a carrier, the next step is to test your partner to find out if he or she is a carrier, too. When both partners are carriers for the same genetic disease, there is a 25% (1 in 4) chance that the baby will be affected.

Pre-pregnancy testing gives you the gift of time. You’ll be able to work with your healthcare provider to learn more about any condition you may be a carrier of, and the potential need for additional testing to help clarify any risks to your future children.

“What does carrier status testing really mean?”

For the types of conditions included in an autosomal recessive carrier status test, having one genetic change — being a carrier — typically does not affect your health. An individual typically does not have one of these genetic conditions unless he or she has two genetic changes in a disease-causing gene. How does this happen? Individuals with autosomal recessive disorders inherit one DNA change from each parent. Thus, carrier testing assesses the chance that each parent carries a single DNA change. When both reproductive partners are carriers for the same condition, each child they have is at risk of inheriting the condition.

More specifically, each child has a 25% chance of being affected by the condition. (It’s important to note, however, that each child in that scenario also has a 75% chance of not being affected.) Some of the more common conditions tested for include cystic fibrosis, Tay Sachs disease and sickle cell anemia,* among many others.

Direct-to-consumer genetic tests, such as the carrier status tests* offered by 23andMe (named after your 23 pairs of chromosomes…your DNA) can provide valuable insights that can help start the conversation with your doctor about what type of genetic screening is right for you. At this time, no genetic test covers every possible risk to your future children so whether you choose direct-to-consumer testing or you have testing through your healthcare provider, be sure to ask about the limitations of the test so that you understand what the test can tell you and what it can’t.

Erynn Gordon
Genetic Counselor
Director of Clinical Development at 23andMe

*23andMe tests can be used to determine carrier status in adults from saliva collected using an FDA-cleared collection device (Oragene●DX model OGD-500.001), but cannot determine if you have two copies of the genetic variant. Each test is most relevant for people of certain ethnicities. The tests are not intended to diagnose a disease, or tell you anything about your risk for developing a disease in the future. On their own, carrier status tests are not intended to tell you anything about the health of your fetus, or your newborn child’s risk of developing a particular disease later in life.The Cystic Fibrosis carrier status test is indicated for the detection of 28 variants in the CFTR gene and is most relevant for people of Ashkenazi Jewish, European, and Hispanic/Latino descent. The Tay-Sachs Disease carrier status test is indicated for the detection of 4 variants in the HEXA gene and is most relevant for people of Ashkenazi Jewish and Cajun descent. The Sickle Cell Anemia carrier status test is indicated for the detection of the HbS variant in the HBB gene and is most relevant for people of African descent.