How genetic testing can help you plan for the future

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Contributed by:
Shannon Wieloch, MS, LCGC
Certified Genetic Counselor and mother of two

When people find out that I’m a genetic counselor, I get a range of reactions, including:

  1. Your job must be so hard! How do you do it every day?
  2. Have you ever made a clone of yourself?
  3. If someone wouldn’t have an abortion, why would they ever do genetic testing?

My responses:

  1. Sometimes it’s tough, but ninety-nine percent of the time, I provide good news.
  2. No clones! (Though it would cut my house cleaning time, it would be WAY too much Shannon for my family to handle.)
  3. What many people don’t realize is that there are so many more things that can be done with genetic testing results beyond making decisions about continuing a pregnancy. It’s a message I try to communicate to all of my patients.

Genetics 101

Before we get into specifics, let’s review some basic genetics. No yawning, I’ll be brief.

You can think of your and your partner’s DNA like two copies of your favorite book series. Harry Potter? The Chronicles of Narnia? Open almost any cell in your body, and you should have 46 chromosomes, 22 numbered pairs and then your sex chromosomes, XX for girl, XY for boy. Each chromosome is like a specific volume in that series, each gene is a word in a particular book, and a mutation is a misspelling in that word. We all have various mutations in our DNA.

Mom will give one complete copy of her book series and dad will give his own version of his complete series. Their child will be a brand new series, one of a billion possible outcomes, who will go on to tell their own unique story.

See, that wasn’t so bad, right?

Carrier screening

The patients I work with have had testing called “carrier screening”, which can tell you if you might be at a higher risk of having a child with a specific genetic condition. Experts recommend that all women planning a family be offered carrier screening.

Most of the conditions included on carrier screens would only affect a child if both mom and dad are carriers (i.e. have a genetic mutation) for the same condition. In this situation, there is a 1 in 4 (25%) chance of the couple having an affected child.

How can I use my results?

There are a number of options for a couple found to be at an increased risk of having a child with a genetic condition.

  • PGD: Many of the patients I counsel are pursuing in vitro fertilization (IVF) for various fertility issues. When pursuing IVF, one option available to high-risk couples is called preimplantation genetic diagnosis, or PGD. PGD involves testing embryos created through IVF and then only transferring embryos that were not found to be affected with the genetic condition in question. This process significantly decreases, though does not completely eliminate, the chance of having an affected child before you are even pregnant.
  • Egg or sperm donor: Another option for those pursuing IVF is to use the donor egg or sperm of an individual who has not been identified to be a carrier of the same condition. Again, this would significantly decrease the risk of having an affected child.

But what if you’re not planning on pursuing IVF?

  • Continue without testing: With natural conception, some parents would elect to continue without further testing, knowing there is a 75% chance to have an unaffected pregnancy.
  • Prenatal testing: Testing during pregnancy through chorionic villi sampling (CVS) or amniocentesis is an option to determine if a pregnancy is affected. Each procedure is quoted to have a risk of 1 in 200 (0.5%) to result in a miscarriage, so a couple would have to weigh this against the 1 in 4 (25%) chance to have an affected child.

Now what if a pregnancy is affected?

Some couples may elect to change the course of their pregnancy. Others may opt to continue their pregnancy. If a pregnancy is continued, a parent may use this time to prepare — emotionally, intellectually or physically — through research and resources that can assist them in caring for a child with special needs.

Regardless of what a couple chooses to do, the choice is theirs and that choice should be supported.

None of these options are easy, though neither is being surprised at the birth of child who requires more than what a couple originally thought.

Now what?

If you are considering carrier screening, the best time to get tested is before you are pregnant. This allows you time to not only test your partner if needed, but also to have a thoughtful discussion about the results and plan accordingly.

Many laboratories offer carrier screening, and the laboratory I work with has a test called CarrierMap which screens for over 300 conditions. We offer all patients the option to discuss their results in detail with a genetic counselor (you might even talk to me!), so they fully understand what the results mean for them and what options are available. Click below to learn more about CarrierMap and request information to share with your healthcare provider.

Learn more about CarrierMap

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