2015年经济学人 生育技术 英国通过三亲婴儿决议（在线收听）

Reproductive technology

Oh, baby

Britain's approval of babies with three genetic parents offers lessons for other countries

“PLAYING God” is what medicine is for. Every Caesarean section and cancer treatment is an attempt to interfere with the natural course of events for the benefit of the patient. Not every procedure should be allowed, but a general sense of what is “unnatural” is a poor guide to what to ban. Transplants and transfusions were once considered unnatural, but now save many lives. That insight is why MPs were right to agree, on February 3rd, that Britain should become the first country to allow the creation of children with genetic material from three people instead of the usual two.

By doing so, they hope to relieve terrible suffering. Faults with mitochondria—the tiny power sources inside cells—afflict about one child in 6,500, or 100 a year in Britain. The many conditions that result, a lot of them agonising and fatal, have no cure. So scientists hope to prevent them at conception, by transferring the healthy nucleus of an egg cell with damaged mitochondria into the body of an egg with functioning ones.

The procedure is not yet allowed anywhere else in the world, partly because it is new and untested in people but also because of the opposition that reproductive medicine often inspires. Mitochondria contain DNA, therefore any child born as a result of such intervention will inherit genes from three people—hence the headlines in Britain this week about “three-parent babies”. If the baby is a girl the genetic tweak in her mitochondria will be inherited by her children, and in turn by her granddaughters' children. It is a “germ-line modification”, and thus irrevocable.

This ethical objection to mitochondrial donation is decisively outweighed by the good that ought to come from it. Mitochondrial disease is a misery to those who have it and a terror to those who fear they might pass it on to their children; curtailing it would be wonderful. The complaint that this is the first step on the road to “designer babies” is as weak as any other slippery-slope argument: approving one procedure does not mean automatically approving others.

A second objection is that this procedure, like any new technique, might not be safe. Those who must bear that risk are not yet born, and so cannot consent to the treatment. But parents already make medical decisions on behalf of their children, even unborn ones. And Britain's bureaucrats, led by the Human Fertilisation and Embryology Authority (HFEA), which regulates fertility treatments, have been scrupulous in assessing risks. The HFEA first granted a research licence for the technique in 2005. Since then, a scientific panel has conducted three reviews of trials in test tubes and in animals. These have given no cause for concern.

From the land of the test-tube baby

That scrupulousness is one reason why the vote passed as easily as it did. Doctors and patients' groups sometimes criticise the HFEA for being too conservative. But its somewhat ponderous, consensus-seeking approach (the HFEA has conducted consultations, ethics reviews and several opinion polls) has helped Britain steer clear both of American-style culture wars and of the lax oversight found in some Asian countries.

Mitochondrial donation will not be the last piece of controversial medicine that the HFEA will need to wrestle with. It is already possible, for example, to sequence the genes of embryos and discard those that carry incurable genetic diseases. Choosing beneficial characteristics is, for now, illegal. But as the human genome becomes better understood, patients may agitate for exemptions. The HFEA, or something like it, offers the best method for evaluating the benefits and risks of such procedures. Sometimes bureaucrats are just what you need.