This milestone isn’t surprising. In 2015, Junjiu Huang of Sun Yat-sen University used CRISPR to edit human embryos, but only nonviable ones that could never have resulted in a live birth. A second Chinese team followed suit the year after. And last year, Shoukhrat Mitalipov of Oregon Health and Science University became the first to use the technique on viable embryos—but never actually implanted any of these into a woman.
Given such work, it seemed almost inevitable that someone would take the steps that He did. “On one level, this isn’t a surprise at all,” says Ellen Clayton, a professor of law and health policy at Vanderbilt University. “On another, this is ...” at which point she was at a lost for words, and heaved a big sigh. “This calls into question the possibility of control, and I think it will exacerbate public fear,” she added.
Societally, the creation of CRISPR-edited babies is a binary moment—a Rubicon that has been crossed. But scientifically, the devil is in the details, and most of those are still unknown.
CRISPR is still inefficient. The Chinese teams who first used it to edit human embryos only did so successfully in a small proportion of cases, and even then, they found worrying levels of “off-target mutations,” where they had erroneously cut parts of the genome outside their targeted gene. He, in his video, claimed that his team had thoroughly sequenced Nana and Lulu’s genomes and found no changes in genes other than CCR5.
That claim is impossible to verify in the absence of a peer-reviewed paper, or even published data of any kind. “The paper is where we see whether the CCR5 gene was properly edited, what effect it had at the cellular level, and whether [there were] any off-target effects,” said Eric Topol of the Scripps Research Institute. “It’s not just ‘it worked’ as a binary declaration.”
Read: A CRISPR pioneer on gene editing: “We shouldn’t screw it up”
Others found little comfort in the assurances from He’s YouTube video. “The mirror analogy here would be if you and I as physicians developed a cold fusion reactor ... without ever having done nuclear reactor design, flipped the switch [without] any safety inspection or even checking if it produced power, then posted [a] vid on Instagram,” said Sandip Patel, an immunologist at the University of California at San Diego, on Twitter.
In the video, He said that using CRISPR for human enhancement, such as enhancing IQ or selecting eye color, “should be banned.” Speaking about Nana and Lulu’s parents, he said that they “don’t want a designer baby, just a child who won’t suffer from a disease that medicine can now prevent.”
But his rationale is questionable. Huang, the first Chinese researcher to use CRISPR on human embryos, targeted the faulty gene behind an inherited disease called beta thalassemia. Mitalipov, likewise, tried to edit a gene called MYBPC3, whose faulty versions cause another inherited disease called hypertrophic cardiomyopathy (HCM). Such uses are still controversial, but they rank among the more acceptable applications for embryonic gene editing as ways of treating inherited disorders for which treatments are either difficult or nonexistent.