Preimplantation genetic testing (PGT) is a technique in which one or more cells is taken from an egg or embryo (fertilized egg) for testing to provide information about the genetic make-up of the rest of the cells in that embryo. In order to utilize PGT, couples must undergo in vitro fertilization (IVF), where the eggs (oocytes) are removed from a woman’s body and mixed with her partner’s sperm in a laboratory. The embryos which are created can be tested on Day #3 after egg harvest and then implanted back into the uterus on Day #5. Alternatively, the embryos can be frozen after the cells are removed for testing and implanted in a subsequent menstrual cycle.
Patients with many inherited familial diseases can have their embryos tested to determine its genetic make-up. Specifically, this would include patients with a history of single-gene disorders (such as cystic fibrosis or sickle cell anemia) and patients with a history of sex-linked disorders (such as Duchenne muscular dystrophy and Fragile X syndrome). In addition, even families in search of a bone marrow donor may be able to use PGT to bring a child into the world that can provide matching stem cells for an affected sibling.
Other patients may also decide to use genetic screening. For some patients with recurrent pregnancy loss, severe male factor infertility, advanced reproductive age or recurrent IVF treatment failures, genetic screening may be used. Genetic screening is different than other types of genetic testing because the testing is looking for any abnormality instead of a specific disease, and as a result is associated with higher rates of false results. At this time, ASRM considers genetic screening for this indication experimental.
If you are uncertain about genetic testing for you, speak with your physician about whether preimplantation genetic testing is right for you.