Preimplantation Genetic Diagnosis (PGD) may be discussed with your doctor as part of your IVF cycle and may be performed in very select cases as part of an IVF procedure to test embryos for a specific genetic abnormality prior to embryo transfer. One or two cells are taken from an embryo and tested on the third day of embryo development, and embryos are transferred back to the uterus after results are obtained on the fifth day of embryo development. While there is a risk of embryo damage from the biopsy procedure, most embryos are not adversely affected. PGD provides couples who possess a risk of having children with a known abnormality the ability to have embryos screened, providing transfer of unaffected embryos. While PGD does not guarantee a genetically normal child, it does decrease the risk of specific abnormalities.
Just a few of the many conditions that can be diagnosed with PGD include cystic fibrosis, Tay-sachs disease, myotonic dystrophy, phenylketonuria, sickle-cell disease, achondroplasia, Huntington's chorea, hemophilia, retinitis pigmentosa, Gaucher disease and thalassemia. PGD has also been used to screen embryos for aneuploidy (abnormal chromosomal number) for patients at risk of having embryos with this condition secondary to age, or for those patients with a history of recurrent pregnancy loss. Genetic counselors are available to determine your risks of any genetic abnormality based on your specific family and medical history.