What is PGD/PGS?
Preimplantation genetic testing identifies genetic problems in embryos during in vitro fertilization (IVF).
Preimplantation genetic diagnosis (PGD) is a part of genetic testing when one or both prospective parents has a known genetic defect, and testing is done on the embryo to determine if it carries that specific genetic defect. Defective genes can cause cystic fibrosis, Tay-Sachs disease, Downs Syndrome, sickle-cell anemia, and many other disorders.
Testing can be done on either 1 cell from a 3-day old embryo containing 6 to 8 cells, or from a piece of the shell of the embryo (trophectoderm) containing several cells. Normally, it is preferable to take a biopsy from a 5-day old embryo.
When is PGD/PGS recommended?
- Women over 35 years of age.
- Couples with a previously affected child.
- Patients with a family history of a chromosomal disorder.
- Women who have experienced recurrent miscarriages.
- Men with severe male factor infertility.
- Cystic fibrosis
- Muscular dystrophy
- Sickle cell anemia
- Tay Sachs disease
- Down Syndrome
- Huntington’s disease
- Mental retardation
- Congenital absence of the vas deferens
- Recurrent miscarriage
- Unexplained still births or neonatal deaths
- Chromosomal syndromes
- And many other disorders
Risks of PGD
PGD can reduce the risk of a genetic abnormality, but cannot guarantee that a problem will always be detected. Chorionic villus sampling and amniocentesis in the first trimester may confirm the results of PGD and PGS or reveal other genetic issues. These first trimester tests, although generally very safe, do present a small risk of inducing miscarriage.