16 July 2008
An ethics task force from the European Society of Human Reproduction and Embryology (ESHRE) is to investigate the application of DNA chip (microarray) technology in embryo screening. Preimplantation genetic screening is used to identify significant chromosomal abnormalities in embryos created by in vitro fertilization (IVF) prior to implantation, with a view to establishing pregnancies with the healthiest embryos to minimize the risk of miscarriage. The British Fertility Society has recently published guidelines on this form of screening (see previous news), which are significantly different from prenatal genetic diagnosis (PGD), used for the definitive diagnosis of specific serious genetic disorders.
Microarray technology makes it feasible to test for the presence of thousands of specific genetic abnormalities or variations simultaneously – but the clinical significance of many is unknown, and might not influence the successful establishment of a pregnancy. Task force chair Professor Guido De Wert, who has launched a consultation process with ten European fertility centres, commented: "One of my concerns is that people who are naive about genetics think that it is easy to pick the best embryo… But even the best geneticists don't know how to interpret how diseases might develop from gene chip information” (see BBC news). The aim of the ESHRE task force is reportedly to assess the potential of ‘gene chips’ for embryo screening and ultimately develop a code of practice to regulate their use. One of the difficulties will be to distinguish between the diagnosis of a specific disease for which the embryo is at high risk due to family history, and screening for numerous other diseases for which the embryo is not at particular risk. Although screening raises additional ethical issues, since both types of tests could easily be performed simultaneously using the same microarray, having different guidelines for each type of test may become impracticable.