Gene Editing—A Revolution From Stem to Stern

The Lancet  Dec 15, 2015  Rebecca Cooney, Editor

Gene editing has swiftly become one of the most promising—and controversial—breakthroughs in genetic engineering.

With the entrance of CRISPR (clustered regularly interspaced short palindromic repeats), a technique using  the Cas9 enzyme to cut strands of the genome at precisely targeted locations to insert, replace, or remove DNA, the manipulation of the genetic basis of human disease has once again come to the fore.


Much of the excitement comes from the sheer versatility of the yet little explored technique as a possible way to preempt, for example, diseases such as Tay-Sachs or sickle cell anemia. But that promise may not come without unforeseen consequences, prompting leaders in the world of genetics to question what the scientific and ethical boundaries of this technology should be.

Dec 1-3, 2015, experts from the leading international scientific groups in this domain at the Gene Editing Summit held at the National Academy of Sciences and the National, co-hosted with the Academy of Medicine Chinese Academy of Sciences and the UK’s Royal Society. The summit brought together researchers and stakeholders from around the world to discuss the scientific, ethical, and legal issues surrounding the current state of gene editing. After days of discussion, the group released a statement to summarize the consensus.

The statement highlighted four areas where caution must be exercised and where continued work is necessary to clarify and quantify the clinical utility of gene editing. The first area is to better elucidate where there is strong basic and preclinical evidence for editing gene sequences in human cells. Of note, the statement makes clear that germline cell editing should not be used for establishing pregnancy. Second, at the somatic cell level, a greater understanding of the risks involved in the individual receiving genetic modification therapy is necessary. Currently, there is little to no regulation for somatic genetic editing. Similarly, there is little oversight with respect to germline cell editing. Here, there is considerable ambiguity around the circumstances where editing might be appropriate. In particular, the capacity of editing to “enhance” human traits or capacities is of great concern. Finally, the statement points to the urgent need to continue the conversation within the international community about regulation around the human genome.

Coming to a consensus on some aspects of science and ethics, though at a crossroads, is far from the end of the story. In fact, the consensus statement serves as a foundation for the next epoch of discussion. On Dec 8, 2015, it was announced that the second wave of the Academies’ Human Gene Editing Initiative was set to commence. Alta Charo, a professor of Law and Bioethics at the University of Wisconsin, Madison, and Richard Hynes, of MIT and Howard Hughes Medical Institute investigator, are set to co-chair the study committee that will steer that next wave of information gathering and buy-in from the scientific community, policy makers, patient advocacy groups, and the public. This is a monumental step in determining the way in which gene editing can and will be employed for human disease. More specifically, the committee is tasked with evaluating the scientific evidence around several weighty issues, including the clinical applications of gene editing in specific human disease states; what the specific risks of gene editing may be in humans and what steps can be taken to mitigate those risks; and what the appropriate ethical, scientific, and legal oversight bodies should be in the USA and internationally.

It is a pivotal time to move forward with gene editing. But to do so will require a firm accounting of what has been accomplished and what might be accomplished through the judicious and thoughtful clinical application of our latest scientific developments.

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