Preimplantation Genetic Diagnosis (PGD) is an alternative to existing methods of prenatal diagnosis for couples with a high risk of transmitting a severe genetic disorder to their offspring. Molecular and cytogenetic analysis is carried out at the level of individual blastomeres, which are obtained from cleavage-stage embryos, resulting from IVF or ICSI. Up to now the following molecular methods have most frequently been used: FISH, for sex determination and the analysis of structural and numerical chromosome abnormalities and PCR for the analysis of mutations in cases of monogenic disorders. Relatively new developments are the use of Comparative Genomic Hybridisation and microarrays.

The conditions for which PGD is available will be discussed as well as the results obtained by the ESHRE PGD Consortium. This Consortium was established in 1997 and consists of a group of more than 50 PGD centres. Since 1999, the ESHRE PGD Consortium has been collating data on referrals, cycles, pregnancies and babies born after PGD. The cumulative ESHRE PGD database holds data on more than 7000 treatments with a total of nearly 37,000 biopsied embryos. Furthermore, data on the neonatal outcome of more than 1,000 children born from PGD have been obtained.