The rapid development and widespread adoption of easy-to-use, inexpensive and effective genome-editing methodologies has changed the landscape of biology. The simplicity of the CRISPR–Cas9 system allows researchers and students to make precise changes to genomes, thereby enabling many experiments that were previously difficult or impossible to conduct.Widespread concern over possible attempts to engineer the human germline (perform gene editing on embryos or gametes for reproductive purposes) led to calls for caution or even a research moratorium (see here). At the conference this week, panels discussed the current technical state of human gene editing, existing and potential governance structures, international perspectives, and social consequences of the technology. The most controversial application of human gene editing – germline editing creating heritable genetic changes – was central to many of the discussions, and the conference oscillated between considering the legitimacy of germline editing and considering the arguably more mundane regulatory control of somatic gene editing. The conference coordinating committee has released a consensus statement that endorses further research on both somatic and germ-line gene editing, subject to existing regulations and oversight mechanisms. The full statement is here. I reproduce the portion of that statement that focuses on the hotly contested issue of germline gene editing:
3. Clinical Use: Germline. Gene editing might also be used, in principle, to make genetic alterations in gametes or embryos, which will be carried by all of the cells of a resulting child and will be passed on to subsequent generations as part of the human gene pool. Examples that have been proposed range from avoidance of severe inherited diseases to ‘enhancement’ of human capabilities. Such modifications of human genomes might include the introduction of naturally occurring variants or totally novel genetic changes thought to be beneficial.As reported by David Baltimore, chair of the conference committee, the members did not recommend either a ban or a moratorium on research into germline gene editing, but they state that any use of gene editing in reproduction at this time would be "irresponsible." In the U.S., the NIH has already ruled out federal funding for such research:
Germline editing poses many important issues, including: (i) the risks of inaccurate editing (such as off-target mutations) and incomplete editing of the cells of early-stage embryos (mosaicism); (ii) the difficulty of predicting harmful effects that genetic changes may have under the wide range of circumstances experienced by the human population, including interactions with other genetic variants and with the environment; (iii) the obligation to consider implications for both the individual and the future generations who will carry the genetic alterations; (iv) the fact that, once introduced into the human population, genetic alterations would be difficult to remove and would not remain within any single community or country; (v) the possibility that permanent genetic ‘enhancements’ to subsets of the population could exacerbate social inequities or be used coercively; and (vi) the moral and ethical considerations in purposefully altering human evolution using this technology.
It would be irresponsible to proceed with any clinical use of germline editing unless and until (i) the relevant safety and efficacy issues have been resolved, based on appropriate understanding and balancing of risks, potential benefits, and alternatives, and (ii) there is broad societal consensus about the appropriateness of the proposed application. Moreover, any clinical use should proceed only under appropriate regulatory oversight. At present, these criteria have not been met for any proposed clinical use: the safety issues have not yet been adequately explored; the cases of most compelling benefit are limited; and many nations have legislative or regulatory bans on germline modification. However, as scientific knowledge advances and societal views evolve, the clinical use of germline editing should be revisited on a regular basis.
However, NIH will not fund any use of gene-editing technologies in human embryos. The concept of altering the human germline in embryos for clinical purposes has been debated over many years from many different perspectives, and has been viewed almost universally as a line that should not be crossed.The NAS contemplates ongoing public engagement with the controversies raised by human gene editing, in the form of an upcoming formal NAS study and the establishment of a publicly accessible forum to continue the discussion. More analysis of the conference and the effects on the current research climate will be posted here.