Genetic testing has been in the news a lot lately. Unfortunately, a lot of what is being said and written is not accurate. While it’s quite a complicated topic, here are five facts that should give you a clearer understanding of the ins and outs of genetic testing, particularly as it relates to IVF. The term used for IVF genetic testing is called preimplantation genetic diagnosis (PGD), which is only one method of prenatal genetic testing.
Healthy Babies, Not Designer Babies
The main reason genetic testing of the fetus is done during IVF is to prevent a genetic disorder from being passed on to a child. Its goal is to help a woman have a healthy baby. Genetic testing during IVF is not being done with the goal of producing the next Einstein or Mozart.
Some Have More To Gain From Genetic Testing than Others
Some diseases run in families and can be inherited by family members. These are called genetic or congenital diseases. Common examples include hemophilia, sickle cell disease, Tay-Sachs disease and cystic fibrosis. The exact chance of passing one of these diseases on to a child varies with the genes of the parents, but a parent with a family history of the disease has a higher than average chance of passing it on. Embryos from such parents are often tested to see if they carry the gene(s) that cause this disease. If they do, a healthy embryo can be substituted.
The eggs of women over 35 often contain chromosomal abnormalities. These women are also good candidates for genetic testing of their eggs/embryos.
Hundreds of Errors Can Be Tested for
Genetic testing is done after fertilization, but before the fertilized egg is implanted in a woman’s womb. One or two cells are removed from an embryo for genetic analysis. Currently, over 100 different genetic errors (mutations) can be tested for, as well as errors in chromosome number and size. What actually is tested for depends mostly on family history and the wishes of the couple.
Not Everyone Has (or Wants) Genetic Testing During IVF
There is no requirement for genetic testing during IVF. If you don’t want it done, it won’t be done. Even people with a history of a genetic disorder in their family often prefer to avoid testing. To other people, genetic testing raises ethical questions. Some genetic diseases do not show up until middle age, while others are merely an inconvenience. Many couples are happier not having to deal with all these issues that genetic testing may raise.
Genetic Testing Isn’t Perfect
Genetic testing is far from infallible. The tests are only done on one or at most two cells, so they sometimes don’t reflect the genetic makeup of the entire embryo. And the test cannot be repeated for confirmation. Couples will still generally need to have chorionic villus sampling (CVS) or amniocentesis done later in the pregnancy as a confirmation. But despite its uncertainties, genetic testing may allow the couples who are most at risk to have a healthy child instead of one with a birth defect such as Down syndrome or hemophilia. And for older women, it may increase the odds of a successful IVF procedure per transfer and a healthy baby.