PGD is a technique used to assess embryos for genetic diseases and chromosomal abnormalities. It involves the removal of one or more cells from embryos before they are transferred. The cells are then screened for any genetic disease that is known to be carried in the family.
PGD can be used to look for single-gene disorders (inherited diseases caused by a single faulty gene) and chromosomal translocations. Unaffected embryos can then be selected for re-implantation. This protects resulting children from inheriting the disease.