Preimplantation genetic diagnosis

Preimplantation genetic diagnosis (PGD) of inherited conditions following in vitro fertilization (IVF) is now clinically well established worldwide and 7000 children have been born. The range of applications includes single gene defects, chromosome aneuploidy and structural abnormalities, and HLA matching, to identify histocompatible embryos for cord blood stem cell transplantation and treatment of existing children affected mainly by blood related conditions. Recently, the use of advanced technologies for genome-wide analysis, such as microarrays, has provided a universal approach for the diagnosis of both inherited genetic defects and chromosomal abnormalities affecting the viability of the embryo. Clinical pregnancy rates have steadily increased with improvements both in the accuracy of the diagnosis and in IVF. Clinical outcomes are similar to those in assisted conception generally, with an increase in prematurity mainly associated with multiple births and no significant increase in congenital abnormalities. Follow up of children born is ongoing but initial studies have been reassuring.