June 30, 2008 — -- A London doctor used genetic screening to help a woman conceive Britain's first baby guaranteed to be free of hereditary breast cancer.
The 27-year-old woman decided to have her embryos screened for an inherited gene that would have left the baby with a 50 percent chance of developing breast cancer. The woman has a long history of breast cancer in her family, and her husband tested positive for the gene.
The embryo screening, called preimplantation genetic diagnosis, entails removing cells from several embryos at the eight-cell stage of development, when they are around three days old. The cells from each embryo are tested for genetic disorders, and any embryo that is found to be free of the screened disorders is implanted in the mother's womb via in vitro fertilization.