A group of British IVF experts has announced that it is about to begin screening embryos for genes which predispose people for early- onset Alzheimer's. This was first done in the US about five years ago. Writing in the newsletter BioNews, three experts from the London Bridge Fertility, Gynaecology and Genetics Centre defiantly anticipate "the usual controversy" about designer babies.

The man who has requested the clinic to screen his embryos has several relatives who died from the condition in their 40s. If he himself is a carrier, half of his children are likely to be affected as well.

The distinctive ethical issue with screening for early-onset Alzheimer's disease is that the person will not develop symptoms for more than four decades, if ever. However, these experts suggest that 40-plus years of a disease-free life is not the only factor to be considered. First of all, screening gives couples a choice between childlessness and risk. "PGD is all about choice for individual patients at risk of transmitting genetic disease to help prevent suffering for their families," they argue.

Furthermore, if couples choose pre-implantation genetic diagnosis, they will be able to avoid the expenditure of "vast physical, emotional and financial resources" in caring for a "middle-aged 'child'" when they are in their 70s or 80s.