Pre-implantation genetic diagnosis.

Genetic disorders are a major cause of miscarriage and fetal death. Pre-implantation genetic diagnosis (PGD) can be used to diagnose genetic defects before pregnancy has occurred by creating embryos by IVF, then removing single cells which are genetically analysed using FISH or PCR. Although successful, the techniques have many difficulties because they are highly specialised and at the extreme limit of sensitivity. Newer techniques, however, can rapidly diagnose multiple defects including chromosomal aneuploidy, sex and single gene defects. Embryonic cells can also be DNA fingerprinted to ensure that contamination has not occurred. As embryo screening can increase IVF success rates and decrease miscarriage rates, it will be increasing offered in routine IVF rather than just those patients at high genetic risk. These new, low cost techniques may ultimately allow PGD to be offered to all IVF patients regardless of risk.