The technique of identifying genetic defects in embryos created through in vitro fertilization (IVF) before pregnancy is Preimplantation Genetic Diagnosis or PGD. It is especially used when one or both sets of parents have a known genetic marker that can result in genetic disease in the baby or/and the couple already have an affected baby so that a healthy offspring can be born.
Following IVF procedure, the embryo is tested to ascertain if it is affected or a carrier of the genetic disease. PGD as a genetic diagnostic technique was developed in the late 1980’s and since then has been refined and enhanced to an extent that it is easy to examine all 23 pairs of chromosomes with minimum to no risk to the embryo.
PGD begins with the process of IVF
- Once the embryos reach 5 days old, a couple of cells are micro-surgically removed. DNA of the cells is examined to determine if the disease-carrying or the problematic gene is present within the cell. This process may take up 6-7 days.
- Once the PGD is completed and it has been established that the embryo(s) are healthy, it is implanted in the uterus.
- As it can take up to a week for the results of the PGD tests to be available, usually all the biopsied embryos are frozen. Once the results are available, embryos that free of genetic issues are implanted in a frozen embryo transfer process and the problematic embryos are destroyed.
Some of the couples that can benefit directly are:
- Carriers of chromosomal disorders
- Sex linked genetic disorders
- Single gene disorders
One of the major advantages of PGD has been that parents can get quite a few genetic conditions tested. As the process for PGD is performed and determined before implantation the couple has a choice to ensure their child is born healthy without some genetic diseases looming on the head.
While there are definite advantages of PGD and it has reduced the chances of certain genetic disorders, we usually advise the couples also to undergo prenatal testing.