It’s in the Genes
Advances in genetic testing are offering women more information than ever before about their genetic makeup and are providing opportunities for empowered decision making related to a wide range of health issues. In this recurring column, experts provide vital information about how genetic testing suits one’s individual needs, potential risks and benefits, and the role of genetic testing in advancing treatment approaches that target cancer and other diseases.
This Is Not Your Mother’s Pregnancy
Three questions to consider about DNA testing— and what you might do with the information
By Shivani Nazareth, MS, CGC
Our mothers may tell us that times were much simpler when they had their children. Quite frankly, they’re right: there was less information available to women about a wide variety of issues related to pregnancy and childbirth. For one thing, amniocentesis was still unheard of until the 1970s.
Today women have the opportunity to understand much more about their pregnancy through a number of prenatal screening tests. These tests use your DNA (or fetal DNA) to determine the health of your pregnancy; they range from expanded genetic carrier screening to cell-free DNA screening (referred to as NIPT, for noninvasive prenatal testing), amniocentesis with microarray, and even preimplantation genetic diagnosis (DNA testing of embryos prior to pregnancy).
While the choice to access this information about your pregnancy is generally a good thing, facing this trove of information can sometimes feel completely overwhelming. If you are thinking about having a baby, here are some questions you should ask yourself.
How much information do I want?
This is a good question to ponder. If you are an information seeker, you may wish to know everything you possibly can about the pregnancy. You may actively seek out data before you even conceive; for example, you may have a carrier screen performed on samples of your and your partner’s blood. Such tests look for recessive conditions, such as sickle cell disease, Tay- Sachs disease, cystic fibrosis, spinal muscular atrophy, and Wilson’s disease. Today expanded carrier screening for more than 100 diseases can determine whether you and your partner share any disease genes that could be passed on to children. Most of the time, results are reassuring and provide peace of mind.
In the case that a risk is detected, you can use the information to be better prepared, research the condition, and seek appropriate intervention or treatment. Or you may choose to start a family using a nontraditional route, such as sperm donation or adoption. On the other hand, you may feel that you want to take things as they come, perhaps the way your own mother did. If you fall into this latter camp, you might wish to skip genetic carrier screening altogether.
What will I do with the information?
DNA testing before pregnancy or early in pregnancy affords you more options, which means you should try to understand your motivation for seeking the information. Pregnancy
is a time when we have a lot less control than we’re used to having. You can do all the right things—avoid smoking and drinking alcohol, eat healthfully, and prepare financially—and still find yourself in a situation that you did not anticipate. That said, there are certain elements of pregnancy over which you have more control; one of those elements is deciding what you plan to do with the information you receive from prenatal tests.
As an example, the cell-free DNA screen that is offered in the first trimester (NIPT) looks at bits of DNA that are floating in your blood during pregnancy and contain clues about the health of your baby. The result will tell you your baby’s chance of having Down syndrome. If it is low, you and your partner may feel reassured. If it is high, you have a choice to make: pursue a diagnostic test that will give you a 100 percent accurate answer (amniocentesis) or wait until the baby is born. If you choose to wait, you can use the time to do research and prepare emotionally, financially, and practically. If you choose to have an amniocentesis, you will have a clear answer, but you also face a minimal procedure-related risk of pregnancy loss. One tip: It is helpful to consult a genetic counselor at this juncture of decision-making. Visit the National Society of Genetic Counselors at nsgc.org to find one near you.
Would I consider ending my pregnancy if the baby were diagnosed with a serious disease?
It is uncomfortable to consider how you would react if you learned through genetic testing that your fetus had a serious condition, and you may not know what you would do until the situation arose. If an amniocentesis result confirms a serious diagnosis, you have another choice to make: continue with the pregnancy and be prepared to raise a child with special needs, or consider ending the pregnancy.
Aside from Down syndrome, which many people are familiar with, there are other conditions that can be discovered through amniocentesis. Some of these conditions can result in a shortened life span, severe intellectual delay, or the need for round-the-clock care. Given this information, how you decide to proceed with your pregnancy is a personal choice, and there are no right or wrong answers. Others may have opinions, but only your opinion and that of your partner matter here.
When you are planning a pregnancy, a discussion with your healthcare provider about your point of view on these three questions is important. Think about why you are choosing to learn about the genetic health of your pregnancy. If you simply want to find out the baby’s sex, you may be better off doing that through a mid-trimester ultrasound, rather than a DNA screen, where other, more serious information is also revealed. On the other hand, you may find that having access to information empowers you to make decisions that feel right for you. Either way, as women we have a tremendous amount of choice when starting our families today. It is up to each of us to decide for ourselves what works for us. That is the real beauty of choice and the silver lining behind being pregnant in these modern times.
Shivani Nazareth, MS, CGC,is director of medical affairs at Counsyl, a DNA-testing and genetic-counseling service. She worked as a clinical genetic counselor for more than 10 years in New York City, most recently at Weill Cornell Medical College. Shivani obtained her graduate degree from the Icahn School of Medicine at Mount Sinai and currently serves on the National Society of Genetic Counselors’ Public Policy Committee.