Two British couples plan to sift through IVF embryos and destroy those with a high risk of breast cancer. An application to test for the couples’ embryos for the BRCA1 gene has been submitted by Dr Paul Serhal, of University College Hospital, London. It will probably be approved, as the UK’s fertility authority has already agreed in principle.

Since babies who carry the gene will not necessarily develop breast cancer and if they do, it will only happen after many years of a (hopefully) healthy life, the ethics of this procedure are far from settled. In its defence, Dr Serhal spoke of the harrowing medical histories of his patients. "We are talking about a killer gene that wipes out generation after generation of women," he says. "You can have a preventive mastectomy, but this is traumatic and mutilating surgery that does not eliminate the risk."

Opposing it was Josephine Quintavalle, of the lobby group Comment on Reproductive Ethics. "There has to be a better way of curing disease than this. It is very likely that in the not-too-distant future there will be a way of treating breast cancer that doesn’t rely on eliminating the carrier instead of curing the disease."