A single cell is dislodged from the embryo with a gentle suction. That cell is analyzed for one or more genetic abnormalities. If it contains a genetic defect, then the embryo from which it was taken is destroyed Typically 3 of the embryos which are free of abnormalities are implanted in the woman's womb. The others are destroyed. Female ovum can be checked for a gene that increases the propensity to develop breast cancer.
Some genetic diseases are sex-linked.
Even if a particular sex-linked disease cannot be detected directly, the PGD method can eliminate all of the male embryos and implant only female embryos, thus preventing the transmission of the disease. The first PGD baby was born in 1989. By 1997, over 30 babies had been born world-wide, following the use of this technique. Dr. Perry Phillips, an obstetrician and gynecologist, is one of the directors of IVF Canada . That's the dream of medicine.