Preimplantation Genetic Diagnosis

Preimplantation genetic diagnosis, abbreviated PGD, is the genetic profiling of embryos prior to implantation, and sometimes even of oocytes prior to fertilization. It is considered in a similar fashion to prenatal diagnosis, and when used to screen for a specific genetic disease its main advantage is that it avoids selective abortion, as the method makes it highly likely that the baby will be free of the disease under consideration. PGD is an adjunct to assisted reproductive technology and requires in vitro fertilization to obtain oocytes or embryos for evaluation; embryos are generally obtained through blastomere or blastocyst biopsy, with the latter technique proving less deleterious for the embryo, so it is advisable to perform the biopsy around day five or six of development.