[Preimplantation genetic diagnosis--developments to expect?]

Preimplantation genetic diagnosis (PGD) has been practiced for over 20 years. It prevents the birth of children with serious genetic diseases by selecting healthy embryos before pregnancy. In France, the initial indications of PGD have been extended in two directions: on the one hand, to allow identification of a mutation combined with embryo's HLA typing, to obtain, at birth, stem cells for therapeutic purposes, and on the other hand, to avoid transmission of late onset diseases without having to test the at-risk parent. Other applications are practiced worldwide but are not allowed in our country, such as social sexing. Technological developments can enable more complex diagnosis, research of several diseases or other genetic traits. It may be useful, for example, to use this possibility to add screening for Down's syndrome at any PDG in older women, when the risk is high. Other objectives were considered but presenting difficulties in their application, not only for regulatory and technical reasons, but also from an ethical point of view.