Pre-Implantation Genetic Diagnosis
Pre-Implantation Genetic Diagnosis (PGD) or Pre-Implantation Genetic Screening (PGS) are therapies used to assist patients with known genetic issues or otherwise unexplained recurrent pregnancy loss. Known genetic problems can include gross chromosomal abnormalities that would place the couple at risk of pregnancy loss or having a child with multiple medical conditions. A patient with a balanced translocation would be an example of this. Examples of other genetic issues would be point gene mutations or deletions resulting in known autosomal recessive diseases, such as cystic fibrosis, sickle cell anemia, or Tay-Sachs. If both members of a couple are carriers of these mutations and wish to reduce the chance of an affected child, then PGD would be an option. Finally, if a couple is suffering from recurrent pregnancy loss presumed to be due to genetically abnormal conceptions, PGS might be of benefit. PGD/PGS both involve in vitro fertilization. On the third or fifth day of embryo development, the embryo is biopsied and assessed for the genetic condition of interest. Only embryos that are thought to be free of the genetic condition are transferred back to the mother’s uterus.