• Elizabeth Kearney

Testing the Embryo

Who should consider testing embryos?

Two types of couples might consider IVF and genetic testing of embryos, or preimplantation genetic testing (PGT). The first are couples who have experienced infertility. The second are those who have a known inherited condition in one of their families. This second group might not even have an issue with fertility.

What genetic testing is done during IVF?

Many IVF centers offer genetic screening of embryos to all patients to improve the odds of a healthy pregnancy and baby. In this type of screening, embryos are checked for chromosome problems. Chromosomes are inside cells and contain the DNA, which is the blueprint for how a body grows, develops, and functions.  Changes in the number of chromosomes, called aneuploidy, can cause problems with development, which may cause miscarriage or lead to severe learning problems or physical birth defects in a live born child. 

If someone with a known inherited condition in his or her family wants to avoid having a child with that condition, IVF combined with genetic testing of embryos might be an option.  The IVF clinic will need to know in advance what the condition is to determine if PGT is available. The two forms of inherited conditions that can currently be identified are disorders caused by changes in single genes or developmental problems caused by a rearrangement of chromosomes. Family Screens from Mainstream Genomics can help decide whether this type of testing is appropriate.

How is preimplantation genetic testing performed?

A couple goes through the IVF process of retrieving eggs and sperm and fertilizing the eggs in a laboratory. The fertilized egg is allowed to grow for a few days until a few cells can be removed from the embryo using a special tool under a powerful microscope. The lab then studies the DNA inside the cell. If there are embryos that are not affected by the specific genetic or inherited condition known in the family, those embryos are transferred to the woman’s uterus.

What are the limitations of genetic testing in IVF?

Not all inherited or genetic conditions can be found through IVF. Although most babies are healthy, all pregnancies have a 3-5% chance for birth defects or other problems with development.  Testing embryos won’t take away this risk entirely because genetic testing only looks for certain conditions.

Also, most IVF physicians recommend that couples who tested embryos still consider confirming the test results during the pregnancy through prenatal diagnosis using amniocentesis or chorionic villus sampling (CVS). As mentioned above, a few cells are removed from the embryo to test them. Usually, the cells’ DNA represents the rest of the embryo accurately, but sometimes there are differences. Prenatal diagnosis through amniocentesis or CVS can confirm the findings.

What are the costs of genetic testing of embryos?

Some insurance plans will cover some of the costs of IVF and genetic testing of embryos if there is a known inherited disease in the family.  Otherwise, you can check with your health plan about its policy for IVF and genetic testing.

More about Mainstream Genomics.

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