Health: Babies-to-go

USE THE phrase "designer baby" in a story and you are guaranteed an easy headline. The image of the tiny tot with Lennox Lewis biceps or a Naomi Campbell pout plays to all our fears of science over-reaching itself, straying into areas better left to nature.

But what is wrong with designing babies? I can think of no measure that would contribute more to human happiness than the elimination of the gene for quarrelling from infant siblings.

This week, the Human Fertilisation and Embryology Authority lifted the lid on the debate with its consultation paper on pre-implantation genetic diagnosis - genetic screening of embryos to eliminate those with defects - while dissociating itself from any suggestion of design. In the sense in which most people understand designer babies - infants endowed with strength, beauty or intelligence - this is, of course, true. These qualities are determined by thousands of genes and the chances of finding an embryo with the right combination from among the handful available in in vitro fertilisation would be much worse than winning the lottery.

There are, however, some nasty medical conditions caused by a single defective gene which might be screened out by the method. That may not make a designer baby but it does amount to choosing a disease-free embryo.

For the pro-lifers, with their accusations of eugenics, this is already beyond the pale. But even for those who support parental choice, there are questions to be faced.

One issue is sex selection. This is not up for discussion in the HFEA paper because it has been banned for social reasons since 1993 and the authority sees no need to reconsider that position. It may be forced to, however, with the imminent advent of sperm-sorting techniques which will make the choice of a baby's sex possible without IVF. Sorted sperm - containing only the male Y chromosome - can be used in artificial insemination which falls outside the control of the HFEA.

The HFEA does allow sex selection for medical reasons. A family with a history of haemophilia is better off having girls (who are unaffected) than boys (who are). But what of the carriers? Is it appropriate to select embryos on the basis, not that they will be affected by the condition but that, depending on their choice of partner, their offspring may be affected? The chain reaches dizzyingly into the future.