Anderson replies

I welcome the chance to respond to the thoughtful letter of King et al. On one issue we absolutely agree: the use of germline genetic engineering for purposes of “enhancement” would be a calamity for society. But concern about potential future misuse should not be allowed to prevent the legitimate development of a technology that can save lives and relieve suffering.

King et al. and their colleagues at the US Council for Responsible Genetics (CRG) believe that the danger is so great that no attempt at fetal gene therapy should be allowed that could result in any germline gene transfer. I disagree. A new technology that can save lives should not be rejected because of a theoretical risk. As a paediatrician I have spent my life attempting to reduce the suffering and death of children. Fetal gene therapy offers a powerful technology that could correct genetic diseases which now produce irreversible damage before birth, so avoiding the need for alternative techniques such as gamete donation, embryo selection, abortion, adoption or non-parenthood.

King et al. are incorrect in stating that fetal gene therapy is “likely to result in genetic changes in fetal germline cells”. Our proposal is to treat the second-trimester fetus (not the embryo), by which time all organ systems have formed. There is no evidence that gene transfer could take place into the primary germ cells even if it were desired. All the published data indicate that germline gene transfer is highly unlikely, or may not even be possible, using present techniques (see, for example, refs 1 and 2). So “heritable changes” are not “deliberate”, and it is incorrect to state that “the proposed experiments should be treated as intentional human germline genetic engineering”.

It is misleading for King et al. to state that other countries should “follow the lead of the United Kingdom, and reject Anderson's proposals”. Our proposals have never been submitted to any UK body. We did not ask the US Recombinant DNA Advisory Committee for approval: we requested that a discussion of these issues should begin. The committee commended us for our actions.

The real issue is how to reap the benefits of fetal gene therapy while avoiding misuse. I believe the best defence for society is an educated public. Therefore I applaud King et al. and the CRG for their commendable efforts to raise public awareness of these issues. We have presented our proposals several years before we will be ready to carry out fetal gene therapy, to allow the public to evaluate our efforts at every stage. If we cannot reduce the risk of germline gene transfer to a minimal level, we will not proceed with our proposed studies.