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An international summit on human gene editing recently concluded with a consensus statement to continue basic research in the controversial area, but warned against any clinical trials or human experiments because “once introduced into the human population, genetic alterations would be difficult to remove and would not remain within any single community or country.”1
So-called “germline editing” is now possible, meaning genetic alterations can be made in human gametes or embryos that can “be carried by all of the cells of a resulting child and will be passed on to subsequent generations as part of the in-human gene pool,” according to a closing statement issued by the organizing committee of the International Summit on Human Gene Editing in Washington, DC.
While there are certainly risks, the benefits could include prevention of severe inherited diseases. Therefore, the committee recommended that intensive basic and preclinical research is clearly needed and should proceed. This basic research should be subject to appropriate legal and ethical rules and oversight on the following:
“If, in the process of research, early human embryos or germline cells undergo gene editing, the modified cells should not be used to establish a pregnancy,” the committee warned.
While IRBs may not be involved in oversight at present, the emerging science warrants careful scrutiny and ethics boards may ultimately have important roles to play. (See guest column in this issue.)
Many promising and valuable clinical applications of gene editing are directed at altering genetic sequences only in somatic cells, whose genomes are not transmitted to the next generation. Examples that have been proposed include editing genes for sickle-cell anemia in blood cells or for improving the ability of immune cells to target cancer. However, there is a need to understand the risks, such as inaccurate editing, and the potential benefits of each proposed genetic modification. Because proposed clinical uses involving somatic cells are intended to affect only the individual who receives them, they can be appropriately and rigorously evaluated within existing and evolving regulatory frameworks for gene therapy, and regulators can weigh risks and potential benefits in approving clinical trials and therapies, the summit committee noted.
“While each nation ultimately has the authority to regulate activities under its jurisdiction, the human genome is shared among all nations,” the panel stated. “The international community should strive to establish norms concerning acceptable uses of human germline editing and to harmonize regulations, in order to discourage unacceptable activities while advancing human health and welfare.”
Germline editing carries the risk of inaccurate editing — such as off-target mutations — as well as the possibility of incomplete editing of the cells of early-stage embryos (mosaicism). Moreover, it is difficult to predict 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, the panel conceded.
Thus, there is an obligation to consider implications for both the individual and the future generations who will carry the genetic alterations. The committee cited “the possibility that permanent genetic ‘enhancements’ to subsets of the population could exacerbate social inequities or be used coercively.” There are profound moral and ethical considerations in the research, which could purposefully or accidentally alter human evolution.
“It would be irresponsible to proceed with any clinical use of germline editing unless and until the relevant safety and efficacy issues have been resolved, based on appropriate understanding and balancing of risks, potential benefits, and alternatives, and there is broad societal consensus about the appropriateness of the proposed application,” the organizing committee concluded. “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.”
Financial Disclosure: Editor Melinda Young, Senior Staff Writer Gary Evans, Managing Editor Jill Drachenberg, Associate Managing Editor Dana Spector, Physician Reviewer Lindsay McNair, MD, MPH, MSBioethics, and Nurse Planner Kay Ball, RN, PhD, report no consultant, stockholder, speaker’s bureau, research, or other financial relationships with companies having ties to this field of study.