4:24 PM
 | 
Aug 03, 2017
 |  BC Innovations  |  Tools & Techniques

The other side of the Rubicon

Embryo study’s success is shifting the topic from ethics to efficacy

Editor's Note: This article was updated on Aug 03, 2017 at 5:07 PM PDT

In the end, it might be the efficacy that guides the ethics. By showing that editing of human embryos using CRISPR can be performed efficiently and without leading to the much-feared slew of off-target cuts, a team at Oregon Health & Science University has changed the conversation around germline gene editing from whether it should ever be allowed to where to start and how to do it safely.

What’s clear is that by conducting a well-designed and highly regarded study, the researchers have moved the field beyond a point of no return, and a wave of new experiments across the scientific community is likely to follow.

This study, published yesterday in Nature, involved CRISPR-Cas9 editing on 58 human embryos carrying a mutation in the MYBPC3 gene that causes hypertrophic cardiomyopathy.

What set it apart from the three previous reports of editing in human embryos, which were all performed in China, were the high success rate and low mistake rate.

Two of the earlier studies were performed in non-viable embryos that couldn’t result in live births; the third involved a small number of healthy, viable embryos. Each paper showed some level of gene correction in the embryos, but produced only a small percentage of incompletely corrected, or mosaic, embryos. Those studies precipitated an outcry of ethical concerns that scientists would surge ahead before demonstrating the method could produce sufficiently high efficiency with the wide margin of safety the scientific community and the public would demand.

By contrast, the OHSU study, which also included researchers from the Salk Institute for Biological Studies, South Korea’s Institute for Basic Science, Seoul National University and Chinese genomics company BGI Group, achieved a more than fourfold improvement in editing efficiency over the Chinese studies and eliminated mosaicism. It produced no off-target cuts in more than 700 sites examined in the embryos and stem cells from the patient.

CRISPR pioneer and University of California Berkeley professor Jennifer Doudna praised the study, calling it “to date the clearest direct step” towards successful gene editing in the human germline.

“I expect these results will be encouraging to those who hope to use human embryo editing for either research or eventual clinical purposes,” said Doudna.

Bioethicist Arthur Caplan agreed, noting the science is “pretty well done, pretty impressive,” and said while the field still needs ethical oversight, this paper will drive research forward.

“With the fact that this is being published in Nature, I would say this is absolutely rocket fuel for more studies,” he told BioCentury.

Caplan is director of the Division of Medical Ethics at New York University Langone Medical Center.

In addition to replicating the results and aiming for continued...

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