Common Misconceptions of Genetic Carrier Screening and Beyond

For many Intended Parents, one of the first thoughts that come to their mind is “Will I have a healthy baby?” While most pregnancies result in a happy, healthy baby boy or girl, the possibility of a genetic disorder being present can be a risk for some. 

While this may be daunting to think about, it’s important to be aware of how one can plan and prepare to mitigate those risks, especially if one of the parents has a medical history that suggests elevated risk.

This article will briefly discuss the different types of genetic tests offered, how they differ, and when they are recommended.

Genetic carrier screening: when is it needed

All humans carry abnormalities in their DNA. This thought often scares people but remember that the vast majority of people don’t even know about them, let alone are affected or show any signs of them throughout their lives. The concern is when there is an abnormality that can be passed onto your offspring and when it can affect them in a harmful or impactful way. One of the best ways to address these concerns is with Genetic Carrier Screening. 

This test is typically performed at the beginning of your IVF journey. Sperm and egg sources would need to be tested as part of their pre-cycle lab work prior to the creation of your embryos. This test is performed either via a blood or home saliva test, and the results usually take around two weeks to finalize. 

If you are a heterosexual couple, this will help you determine if the embryos will need  PGT-M  testing (more on this below). If you’re using an Egg Donor, this will help you to determine a good egg donor candidate. Remember that the intention of these tests is to determine whether your sperm and egg sources have any common mutations that could be passed onto your offspring. 

*Note: PGT-A is the new name used for PGS testing. PGT-M is the new name used for PGD testing. 

The difference between genetic carrier screening and PGT-A or PGT-M tests

Genetic Carrier Screening is not to be confused with the PGT-A or PGT-M tests. Although they all test for diseases and mutations, there’s an important difference between the three tests.  While Genetic Carrier Screening is part of every journey as part of your pre-cycle lab work, PGT-A tests all 23 pairs of chromosomes for structural/numerical abnormalities. 

Meanwhile, PGT-M is performed when there is a specific concern or need in relation to a singular mutation. PGT-M tests are often performed when there is a rare disease that isn’t commonly found on a standard panel. These tests typically require the use of a probe, or a customized panel that uses samples from the sperm/egg sources, as well as the embryo. In some cases, other members of the biological family to the sperm/egg sources may also be needed.

For both of these tests, it’s important to note that they are performed after embryo creation but before implantation. Being negative for a carrier does not eliminate the risk of chromosome abnormalities of the embryos. 

To learn about PGT-A and PGT-M testing, please click here. 

What does it mean to be a “carrier” of a genetic disorder? 

It is often asked whether being a ‘carrier’ of a disease means that you have that disease. If you are positive for being a genetic carrier, it means that a disease-causing variant was found, and you are a carrier of one or more disorders tested. 

However, being a carrier doesn’t necessarily affect your own health. We are all carriers of one or more genetic disorders. This doesn’t mean that we necessarily ‘have the disease’, yet it does mean that there is an increased risk of having a child with that disorder. 

A genetic counselor can discuss your specific case depending on the type of carrier. If you are planning a pregnancy, have a family history of a genetic disorder, or planning to use donor eggs or sperm, you should consider this test.

If you have questions about genetic testing, please reach out to our specialist by clicking here.