Why I Chose to Have Genetic Testing

Alexis

New mom, Christina Barnes, MSN, RN, CPNP-PC, shares why she chose to have genetic testing done before trying to conceive

My husband and I chose to have genetic testing done before we started trying to conceive. As excited as we were about becoming pregnant, we felt anxious about the fact that so much of conception and pregnancy was outside of our control. We are both planners, and we don’t feel good about making important decisions without first researching and organizing any and all relevant information (maybe sometimes a little too extensively). We like to know our risks, investigate what we can do to reduce those risks and have a plan to manage those risks. When it came to getting pregnant, the amount of information available on how to have a healthy pregnancy was overwhelming. What were the best foods to eat while trying to conceive? What activities should I avoid in the first trimester? What medications could harm the growing fetus? Perhaps most importantly, what (if anything) could I do to make sure my baby would be born happy and healthy? Each website seemed to have different answers to those questions, and I was usually left more confused at the end of these wild internet dives than when I started. Prenatal genetic testing gave us concrete information we could use to help us make decisions about conception and pregnancy.

 I am a Pediatric Nurse Practitioner and I have worked with many amazing children and families in the Pediatric and Neonatal Intensive Care Units, as well as pediatric primary care and surgery clinics. A large part of my work has been caring for children with genetic diseases present at birth. I am always in awe of how strong, resilient, and capable children are, especially when faced with a debilitating illness. Part of my anxiety about becoming pregnant was my first-hand experience with children who have genetic diseases; I wanted to do everything I could to make sure that my child would experience life without disease or disability. Of course, some of this will always be outside of our control, but I wanted to figure out exactly what I could do to reduce the risk that my child would be born with a genetic disease.

 Genetic diseases are caused by mutations in one or more genes in a person’s DNA. Genetic diseases are inherited from one or both biological parents and are present at birth. There are two types of inherited genetic diseases: dominant and recessive. In a dominant genetic disease, the child only needs to inherit one copy of the mutated gene from one parent in order to have the disease. This mutated gene “dominates” the other unaffected gene, essentially overriding it and causing illness. An example of a dominant genetic disease is Marfan syndrome. If I had Marfan syndrome and my husband did not, my child would have a 50 percent chance of inheriting my dominant defective gene and having the disease itself. There are no carriers of dominant genetic diseases; you either have the mutated gene that causes disease or you do not.

 In a recessive genetic disease, the child must inherit two copies of the mutated gene, one from each parent, in order to have the disease. If the child only inherits one copy of the mutated gene, then the child is a carrier of gene but does not actually have the disease. An example of a recessive genetic disease is cystic fibrosis. If my husband and I are both carriers of cystic fibrosis, meaning we each only have one copy of the recessive gene but do not have the actual disease, then our child has a 50 percent chance of being a carrier. If we are both carriers, our child has a 25 percent chance of inheriting two copies of the mutated gene (one from each of us) and actually having the disease. Our child also has a 25 percent chance of inheriting no copies of the mutated gene and is unaffected.

Prior to genetic testing, my husband and I had no idea whether we were carriers for any mutated genes that cause these illnesses. As carriers, we would not have symptoms of the disease; we would simply carry the gene in our DNA. I have worked with many families with healthy parents who were surprised to discover after birth that their child had been born with a recessive genetic disease, such as sickle cell anemia or cystic fibrosis. These parents had no idea that they were carriers for the disease, and sometimes even had multiple other healthy children prior to this child. Their other children would have a 50 percent chance of being carriers (inheriting one mutated gene from one parent) and a 25 percent chance of being neither carriers nor ill (inheriting no mutated genes from either parent). So, it is not only possible but also probable that parents who are both carriers of disease could have healthy children naturally.

There is no right or wrong answer on whether or not to undergo genetic testing; many couples choose not to have testing done because they know it will not change their decisions related to conception and pregnancy. Many patients have told me that they want their child’s creation to be in God’s hands, or that they wouldn’t alter the course of pregnancy because of a positive genetic diagnosis. I completely respect and empathize with that, and I truly believe that there is no right way to go about creating a family. If you are interested in prenatal genetic testing, ask your OB-GYN or Nurse Midwife for more information on where and how to complete the tests.

My husband and I felt that it was important to undergo genetic testing before we started trying to conceive, rather than wait until after we were already pregnant. If we were both carriers for the same disease, we wanted to be able to talk about our options for conception before we had a fetus that may have been affected. We wanted to prevent disease, rather than be in a position where we had to react to the diagnosis of a potentially debilitating or fatal disease.

What would we have done if we found out that one of us was a carrier for a recessive disease but the other was not a carrier for that disease? Nothing. Our child would be at risk of inheriting one mutated gene, but would not be at risk of having the disease. Both parents must pass on one copy of the mutated gene in order for the recessive disease to be present. As it turns out, I was a carrier for a rare recessive genetic disease, but my husband was not a carrier for that disease.

What would we have done if we found out that both of us were carriers for the same recessive genetic disease? This answer is a little more complicated. According to our genetic counselor, these would have been our options:

1. Conceive naturally, knowing that there is a 25 percent risk for the baby inheriting the disease. We could test the fetus and make a decision on whether to continue or terminate the pregnancy based on the prenatal diagnosis.

2. Create embryos with my egg and my husband’s sperm and test the embryos. Implant healthy embryos (those that do not have two copies of the mutated gene) through IVF. Our providers would need to know which disease(s) we were both carriers for in order to test the embryos for those specific diseases.

3. Use a donor egg or sperm from a donor who is not a carrier for the particular disease.

4. Conceive naturally and do not test the fetus for disease. Test the baby after the baby is born and if the disease is present, provide available care to the baby to help manage the disease.

 Fortunately, we discovered that we were not carriers for any of the same diseases. If we had been, though, prenatal testing would have given us the opportunity to have these difficult discussions and understand how we each felt about our potential options. With these reassuring genetic testing results, we were ready to start our new family. After five months we were pregnant, and today we are the proud parents of a happy and healthy 4-month-old son.

To learn more about our Genetic Services and our genetics team check out our genetics resource page here.