Biologists’ proposal to regulate human germline editing is flawed

Eighteen biologists recently published a commentary in Nature arguing for a moratorium on clinical human germline editing. The presidents of the U.S. National Academies of Science and Medicine and the British Royal Society endorsed the call. Although there is much in the moratorium proposal that is valuable, there are two reasons why it should not form the basis for policy.

• It puts unnecessary restrictions on the use of technology that could eliminate incurable diseases now.
• It is unduly permissive of what it envisions for the future allowing countries to choose how to modify the human genetic profile. 

The biologists call for a five-year voluntary moratorium on clinical germline editing to be adopted by all countries. During that period, issues such as safety, efficacy and desirability, among others, would be worked out. After that, each country would be left to formulate its own policy so long as it gives public notice, engages in international consultation, carries out a transparent evaluation, and shows that it has widespread internal social support. The biologists recognize that the situation may be quite different between correcting deleterious genes or carrying out genetic enhancement. 

But there is a problem with this proposal. The first problem is that the five-year period is both arbitrary and, in some contexts, unnecessarily long. There is a small but not empty set of diseases that have no effective treatment and are caused by single genes with high penetrance. That means an individual with that gene will almost always get the disease. These include cystic fibrosis, Huntington’s disease and muscular dystrophy. Unless we are unwilling to tolerate germline editing under any circumstances, there is no rational ground to deny the desirability of removing these genes from the human population, and to do so now.

This does not solve the issues of safety and accuracy of the new gene editing technologies. However, the U.S. National Academies have already convened two panels to study these questions and issued a detailed report in 2017. The general concerns about technological safety and efficacy are well known, and it is highly unlikely that anything new will emerge from five more years of discussion. What is not known is how safe and effective each individual attempt to modify a single targeted gene will be.

A rational strategy would be to establish strict criteria to identify targets for germline modification such as the diseases mentioned earlier. Next, very stringent criteria, such as success with somatic gene therapy (without touching the germline) should be established to demonstrate success at meeting safety and efficacy standards. Once these conditions are met, and only then, germline editing should be allowed to proceed.

It may take less than five years to meet these conditions for a particular gene, but it may also take a lot more. There should be no arbitrary limit. This is not a carte blanche for human germline editing. Rather, it is a proposal to permit it now for a very limited set of genes. This proposal will not be acceptable to those who would not permit any human germline editing, but that disagreement will likely remain well beyond five years.

The second problem with the biologists’ proposal is that in the long run, it would allow some countries to choose genetic enhancement for intelligence, or for fairer skin, or for sporting ability. However, what is at stake with germline editing is the genetic future of the human species. The biologists endorse an illegitimate cultural relativism: They do not even offer any reason why countries are the appropriate units for these discussions and how relying on them would not simply endorse cultural prejudices. They also do not address the important issue that what a culture finds desirable may reflect ethically indefensible social power relations.

Addressing these issues will require a global discussion that may well last longer than five years. But perhaps the wisest policy, for the time being, may be to disallow germline genetic enhancement altogether.

Sahotra Sarkar is a professor of philosophy and integrative biology at The University of Texas at Austin.