Pre-implantation genetic diagnosis

Pre-implantation genetic diagnosis (PGD) is the detection of a genetic condition in an embryo prior to its implantation. A single cell is taken from a pre-implantation embryo and subjected to genetic diagnostic techniques, and only those embryos found to be free of the condition are selected for return to the uterus. This avoids the initiation of an affected pregnancy but requires couples who carry a serious genetic disorder but who may not be infertile to undergo assisted reproduction techniques. Pregnancy rates following PGD are lower than for a regular in vitro fertilisation (IVF) cycle and the congenital malformation rate is comparable to that with intracytoplasmic sperm injection (ICSI). This article describes these aspects of the PGD technique, as well as considering future developments.