Is Embryo Genetic Testing the Right Choice for You?

There are many questions in life that others could answer for you: Should you buy a house? Should you buy that Porsche that you have always wanted? Will exercise cause you to lose weight? Should you go to the movies tonight instead of staying at home and watching TV?

However, there are just as many questions—if not more—that only you can answer for yourself. You know yourself best and only you know what is right for you. Answering a difficult question is not so much about knowing the answer but it is more about what you will do with it. What will the next steps be? Some decisions are inherently risky and part of the reason why only you can answer some questions in life is because those are largely only your risks to take.

Everyone wants to have a healthy baby. Like with genetic screening, prenatal testing, or even IVF treatment, however, one such question is whether you should or should not do embryo genetic testing for genetic disease or chromosomal abnormalities (genetic abnormalities) in order to reduce the chances of birth defects. Presumably, you and your partner have either decided to conceive or have done so already and now you would like to know whether to look into the future of your child’s life either before creating it or before it is born.

Again, what you deem to be the right choice is largely up to you. While some parents deem it their responsibility to know, whether they decide to have a baby that they know is at risk of a genetic disorder or not. And yet others opt out on moral grounds, deciding that they will have the baby no matter what. Whichever option you decide to choose, it doesn’t hurt to know what the options are and what is available.

Embryo genetic testing is typically referred to as prenatal genetic testing, and it essentially provides future parents information about the chances of their fetus developing certain genetic disorders that are caused by changes in genes or chromosomes. For example, aneuploidy is a condition in which there are either not enough (missing) or too many chromosomes. Trisomy and monosomy, on the other hand, refer to disease situations where there is an extra chromosome or a missing one, respectively. Changes in genes that cause inherited disorders such as sickle cell disease, cystic fibrosis, Tay-Sachs disease to name a few, are called mutations. In these situations, each parent has to be a carrier, or have the mutation, in order for their child to be affected.

So, before going into the actual test options, it is important to differentiate between the two contexts under which embryonic genetic testing is performed. Prior to that, a type of screening called carrier screening can be performed on parents (or those thinking of becoming parents) in order to find out whether or not they are potential carriers of a genetic disorder that they may pass on to their baby.

If a baby is conceived via in vitro fertilization

If a baby is conceived via in vitro fertilization (embryos are created via a combination of eggs and sperm in the lab), the testing is called preimplantation genetic testing (PGT), of which there are two types. Preimplantation genetic screening (PGS) is typically for women who do not have a known pre-existing increased risk of genetically abnormal embryos. It tests to make sure that the number of chromosomes is normal and it is typically recommended either for older parents-to-be, for couples who have already undergone several rounds of fertility treatments or who have experienced multiple miscarriages. Preimplantation genetic diagnosis (PGD), on the other hand, is used by couples who know that they carry risks of passing on genetic disorders as means to find out the chances of passing it on to their child. PGD investigates whether embryos carry genes that may cause specific diseases such as cystic fibrosis, muscular dystrophy, sickle cell anemia, or hemophilia. Couples who decide to conduct PGD don’t typically have fertility issues.

For couples who have conceived via IVF, PGT may not have all the answers. Still, pregnant women should undergo prenatal testing to make sure their embryo is developing as anticipated. Pregnant women have access to two main types of prenatal genetic tests, prenatal screening tests,and diagnostic tests. Prenatal screening tests inform parents about that chances of their fetus having an aneuploidy and a few other disorders. Prenatal diagnostic tests, on the other hand, tell the parents whether or not their fetus actually has a certain disorder. These tests are done on fetus cells or on the placenta. A pregnant woman’s blood or ultrasound exams can look for aneuploidy while brain defects as well as some defects of the stomach, heart, or facial features.

Pregnant women are screened throughout the entire pregnancy. First-trimester screening (between weeks 10 and 13) includes blood tests and ultrasound screens for risks of Down Syndrome or any other type of aneuploidy. It also checks for the heart, stomach wall, and skeletal abnormalities.

Second-trimester screening tests for Down Syndrome, trisomy 18 as well as brain defects (between weeks 15 and 22). Additional tests (between weeks 18 and 20) tests for major physical abnormalities in the brain, spine, face, stomach, heart,and limbs.

Combined first- and second-trimester screening is also available and, as the name states, it is a combination of the first- and second-trimester test results. Taken in combination, they are a lot more powerful in terms of their predictions. However, they are only available in the second trimester.

In terms of accuracy, as with any other test, there is a possibility that the tests may imply the fetus has a disease when,in fact, it does not (false-positive) or the opposite, that it does not have a disease when in fact it does (false-negative). Rates for each vary and doctors are typically informed in regards to the odds of each.

Given the options, whether or not you would like to go through embryo genetic testing is a personal choice and entirely up to you and your partner. Each situation is individual. And, as with everything in life, there are pros and cons to this, as well. If couples decide to go down this route, it is important to discuss the options with a professional health care worker who can help guide them in the best direction for them.

Laura Day
 

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