Testing laboratory-fertilized embryos for genetic diseases before implantation can be done through a procedure called preimplantation genetic testing (PGT) or preimplantation genetic diagnosis (PGD).
What’s the big deal about PGT? PGT can test an embryo for potential genetic risks before beginning a pregnancy. The testing reduces the mystery parents-to-be face when having children compared to an unassisted pregnancy.
The potential genetic risks that PGT can test for are:
- Chromosomal abnormalities: genetic disorders that can be defined as having a missing or extra piece or whole chromosome beyond the expected 46 chromosomes from both parents. Some chromosomal abnormalities include:
- Down syndrome – An extra chromosome 21
- Edward syndrome – An extra chromosome 18
- Turner syndrome – Having one X chromosome, only affects females
- Single gene disorders are caused by a change in the genetic makeup of a single gene. Single gene disorders can have different inheritance patterns, such as dominant and recessive genetic disorders including:
- Cystic Fibrosis
- Tay Sachs disease
- Hereditary Breast and Ovarian Cancer Syndrome (HBOC)
How does science work behind PGT?
We all remember from high school biology how a sperm meets an egg and starts dividing into new cells. PGT uses embryos developed via in vitro fertilization (IVF), about three days into development when the embryo is only about six to eight cells in total. A laboratory technician takes one or two cells from the embryo as a test sample—enough to run tests without harming the remaining cells. PGT looks for abnormalities in the chromosomes, as well as different genetic conditions that run within family lines, like single gene disorders.
Who typically receives PGT?
In most cases, parents who participate in PGT are already aware of their hereditary risks. They can include women with a history of miscarriages or an increased risk for a chromosome abnormality due to age, or couples who have an increased risk for single gene disorders/chromosomal abnormalities. Some couples choose to use PGT for other reasons. It’s important to talk to your medical professionals to determine what’s best for you and your family.
