How is PGD Testing Performed at a Denver Fertility Clinic?
- Posted on: Dec 22 2012
Preimplantation genetic diagnosis (PGD) is a technique used to identify genetic abnormalities in embryos before a woman gets pregnant. Chromosomal abnormalities are common in embryos, and are one of the main reason women fail to conceive with IVF (or spontaneously) as they age.
It is known that about 60% of embryos in women under 35 years of age and 80% of embryos in women over the age of 41 will be chromosomally abnormal. Preimplantation genetic testing is used to identify genetic defects in embryos created through assisted reproduction (IVF) prior to the embryos being implanted in a woman’s uterus, and hopefully increasing the likelihood of a normal pregnancy.
In general, there are 2 types of preimplantation genetic testing. Preimplantation Genetic Diagnosis (PGD) and Preimplantation Genetic Screening (PGS). PGD specifically refers to the genetic testing that occurs on an embryo from parents known to carry a genetic abnormality. The embryos created for the couple are tested to see if the embryo(s) carries the same genetic defect as the parent(s). PGD testing can occur for genetic diseases such as sickle cell disease, cystic fibrosis, spinal muscular atrophy etc.
There are 100’s of diseases that can be screened for with PGD. PGD can also screen for chromosomal abnormalities, if the parents carry a balanced translocation. The benefit of PGD is that the testing occurs on the embryo or egg during in vitro fertilization prior to pregnancy.
Most other testing methods occur after pregnancy has taken place, which causes a major dilemma for people, forcing them to choose between carrying the baby to term or terminating the pregnancy. The second type of testing is called Preimplantation genetic screening. This testing screens embryos for chromosomal abnormalities prior to implanting the embryos in the uterus.
This technique helps decrease the chance of a woman of advanced age (>35 yo) from having a child with a chromosomal abnormality (such as Down’s Syndrome). Both of these types of Preimplantation testing can be performed at Rocky Mountain Fertility Center, a Denver fertility clinic.
The technique of Embryo Biopsy
Embryo biopsy is a method that tests the actual embryo itself. PGD testing using the embryo biopsy method occurs when one or two cells are removed from an embryo.
PGD embryo testing occurs on the third day of embryo development. By the third day following fertilization of the egg the embryo reaches the cleavage stage which allows a cell or two to be removed for testing.
The embryo is held in place at a Colorado fertility clinic through gentle suction while an opening is made using a microscopic needle or laser. Since the embryo is at a very early stage of development removing a cell does not harm it. The cells removed are then tested for the genetic abnormality.
Posted in: Genetics