PGD is short for ‘pre-implantation genetic diagnosis’. This procedure allows for the genetic investigation of embryos, thereby reducing the probability of the birth of a severely diseased child. PGD is utilised when couples are at a very high risk of having a baby with a genetic disorder, e.g. a chromosome abnormality, cystic fibrosis, haemophilia, Huntington disease or a severe neuromuscular disease.
PGD requires IVF. Once ova have been fertilised by sperm outside the female’s body, one cell is removed from each three-day-old embryo. These cells are then screened in a laboratory for the presence of the parent’s hereditary disease. On the basis of the results of this screening, doctors will decide on the fourth or fifth day following the fertilisation which embryos are eligible to be implanted in the woman’s uterus. Only embryos which do not carry the genetic disorder for whose presence they were screened will be implanted. Couples have a one-in-four chance of conceiving following implantation of the ova.