Preimplantation Genetic Testing

Preimplantation Genetic Testing (PGT)

PGT (also known as preimplantation genetic diagnosis or PGD) is a medical procedure that allows people who carry an inherited mutation linked to cancer (such as BRCA1, MSH2, etc.) to have children who do not have the mutation. The process  requires the same steps involved in assisted reproductive technology (ART). When the embryos reach a certain size (at day 5-7), a few cells are removed from the outer part of the embryo—from cells that help form the placenta, (these cells are not required for normal embryo growth). The DNA from the removed cells is checked for the presence of the genetic mutation. At the same time, the embryos may be screened to ensure they have the correct number of chromosomes in order to maximize the chance of a successful pregnancy and healthy child. This process identifies the healthiest embryos that do not carry the mutation. These embryos can later be thawed and implanted.

Men with mutations have a 50/50 chance of passing on their mutation to each of their children. As with women, men with mutations can prevent passing on the mutation to children through PGD. For men, the PGD process requires their spouse or partner to undergo the steps involved in ART first. 

PGT is the only way to determine whether an embryo contains a genetic mutation prior to pregnancy. There is currently no way to test the eggs or sperm for a mutation prior to fertilization.