Sir

You recently published a full-page report of a Californian symposium on germline gene therapy, and a leading article, without a single mention of preimplantation genetic diagnosis1.

If a couple are at risk of having a child with a serious genetic disease, it is now possible for them to have their embryos screened at the eight-cell stage, after in vitro fertilization, to ensure that only unaffected embryos are transferred to the uterus. Only in the very rare cases where both partners are sufferers from a recessive condition that allows survival to reproductive age, such as cystic fibrosis, will no unaffected embryos be generated. As 10-20 embryos could be produced from a single egg recovery, it would not be difficult also to avoid the birth of carriers if that was desired.

Most couples would surely prefer to avoid the transfer of affected embryos, rather than seeking to tamper with their DNA at such an early stage, with possibly unpredictable consequences. Leroy Hood, chair of molecular biotechnology at the University of Washington, said: “We are using exactly the same kinds of technologies that evolution does”. For those who know anything about evolution and its many failures, this is hardly a strong recommendation.

James Watson is reported as saying: “Scientists should proceed unhindered towards germline engineering”. Either he has forgotten that the simpler and safer technique of preimplantation genetic diagnosis, already in clinical use, renders germline gene therapy for genetic diseases virtually pointless, or it is germline engineering for genetic enhancement towards which he wishes to proceed unhindered?

If it is the latter, he should say so. How about it, Jim?

Sir — One statement in your recent leading article about the consequences of germline gene therapy1 is unfortunately familar: “Our first task should be to take a long, hard look at [what] is likely to be involved — both scientifically and ethically”. This recalls “Government, religious, civic, and scientific leaders should encourage widespread public discussion of the pros and cons of germ line gene therapy”2 and, from a Commentary in Nature, “timely ethical discussion of this issue, before germline gene therapy in humans is technically feasible, may assist future policy-makers in their deliberations”3.

Indeed, this apparent concern was voiced in one of the first official inquiries into the subject: “The novelty of gene splicing ought not to erect any automatic impediment to its use but rather should provoke thoughtful analysis. Especially close scrutiny is appropriate for any procedures that would create inheritable genetic changes”4.

As technical advances make germline gene therapy an even more imminent possibility, one can ask, what has happened in the intervening 16 years? Why has this debate not reached a broader audience? And when will the debate spread beyond the offensive pronouncements of James Watson, who, when once asked if he feared that genetic engineering could be used for ‘positive eugenic’ ends, replied, “It's not much fun being around dumb people”?