Preimplantation Genetic Diagnosis (PGD)

PGD (also known as Preimplantation Genetic Testing or PGT) is a medical procedure that allows people who carry an inherited mutation linked to cancer—such as BRCA1, MSH2, PALB2, etc.—to have children who do not have the mutation. The process is 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 that would one day form the placenta if it implanted and turned into a pregnancy. The removed cells’ DNA is checked for the presence of the genetic mutation. At the same time, most embryos also are 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 sons and daughters. 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. 

PGD 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.