The Science and Ethics of Editing Humans

On Sunday night, November 25, 2018, I finished dinner at my home in California and sat down to my computer. As I pulled up my email, a message sent at 7:37 that evening from a friend caught my eye, mainly because of its subject line—“CRISPR babies.” The email contained a link to a news story by Antonio Regalado, a reporter with MIT Technology Review. The title of the story more than caught my eye: “Exclusive: Chinese Scientists Are Creating CRISPR Babies.” In it, Regalado revealed that a Chinese scientist Dr. He Jiankui was planning to use the DNA editing tool CRISPR (which stands for “clustered regularly interspaced short palindromic repeats”) to change the DNA of human embryos that would be transferred into women’s uteruses for possible pregnancy and birth—“CRISPR babies.”


A quick look at my (exploding) Twitter feed almost immediately led me to an Associated Press story by Marilynn Marchione. That story was based on at least seven weeks of discussions with Dr. He and his colleagues. It confirmed and took further Regalado’s story (though without any reference to it), saying nonidentical twin girls had already been born from CRISPR’d human embryos. And just about the same time, Dr. He posted a set of videos featuring himself and his colleagues on YouTube, discussing these births.

Dr. He claimed to have overseen the use of CRISPR to modify a gene in the human embryos that is called CCR5, a gene known to be important in allowing HIV to infect some human cells. His goal was to make the gene inoperative and thus deprive HIV of that gateway for infection. Two edited embryos, of nonidentical twin sisters, were transferred into their mother’s uterus sometime in late March or early April 2018. Sometime in October, somewhere in China, they were born.

Regalado had first posted his article at about 7:15 Eastern Time on Sunday night, but by then it was already after 8:00 on Monday morning in Hong Kong, where the Second International Human Genome Editing Summit (“the Summit”) was due to open the following morning. The Summit, which followed a first summit in December 2015, had been organized by the U.S. National Academy of Sciences, the U.S. National Academy of Medicine, the U.K. Royal Society, and the Hong Kong Academy of Sciences. The meeting was a big deal. Dr. He had fairly recently been added to the list of speakers, though not to talk about CRISPR’d babies. None of the organizers seem to have learned about his actions earlier than the following Thursday; almost all the rest of the world was taken totally by surprise. But his experiment would clearly dominate the Summit and its coverage.

That evening reminded me of another Sunday, more than 20 years before. On Sunday, February 23, 1997, at about 11:00 a.m., my then-dean called me at home. I was not accustomed to getting phone calls at home from my dean and started searching my conscience. I did not have long to worry—he said to me, in excited tones, something like “They’ve cloned a sheep! I thought you should know.”

Dolly, the world’s first mammal cloned from adult cells, was born in early July 1996, but her birth was kept secret until the researchers, Ian Wilmut and colleagues from the Roslin Institute in Scotland, could publish their scientific paper on her. On the Friday before, Nature had sent out its usual press release about its upcoming issue, which included the scientific article on Dolly. Following its usual practice, the story was embargoed until the following Wednesday afternoon, just before the journal’s Thursday publication. The distribution of the press release under an embargo is intended to allow journalists time to prepare well-researched stories about an article that will give that article, and the journal, some immediate publicity. Journalists are expected to respect these embargo dates. Instead, the Observer, a British newspaper, ran the story as a front-page exclusive in its Sunday, February 23, edition, and the news flashed immediately around the world.

I don’t remember what I said to my dean, but I do remember thinking, “Things are about to get interesting.” On Sunday, November 25, 2018, I had the same reaction. Both times, I was right.

This book is my reaction to the Dr. He “experiment,” an experiment that feels like a cross between bad fiction and reckless fiasco, shrouded in a deep fog of secrets. Part I of the book provides some background to the Dr. He announcement. Its first chapter describes what Dr. He actually did, as much as we know, which is still surprisingly little. The second and third chapters explain human germline genome editing and CRISPR. The fourth and fifth chapters describe the ethical discussions about and legal status of human germline genome
editing before November 25, 2018.

Part II details the revelation of Dr. He’s experiment in November 2018 in the sixth chapter. The seventh and eighth chapters talk about the fallout from those revelations.

Part III of the book deals with assessments. It weighs the Dr. He experiment in chapter 9. (Spoiler alert: I conclude it was grossly reckless, irresponsible, immoral, illegal, and probably fattening.) Chapter 10 lays out some immediate responses that the scientific community (“Science”) in general should have made, as well as some that China should have done, and describes what has been actually been done.

Part IV, the final part, asks more broadly about human germline genome editing: “Now What?” Chapters 11, 12, and 13 look at the technique broadly, not just in the context of the Dr. He experiment. Chapter 11 asks whether the technique is inherently bad (I conclude it is not). Chapter 12 looks at other problems human germline genome editing may cause. And chapter 13 examines the other side of the cost/benefit analysis—would human germline genome editing be very good for anything? Chapter 14 analyzes what kinds of safety testing we would want to apply if we decided seriously to explore going forward with human germline genome editing. And chapter 15 weighs the public policy options of a total ban or regulated use before ending by trying to answer how decisions about this technology should be made. And then, at the end, you get the conclusion.

This book is not entirely second- and thirdhand reporting by me. I was involved importantly in one of the events it discusses and secondarily in some others. I’ve followed the discussions closely for over five years, and I know personally many of the characters in this play (whether tragedy or farce remains to be seen). All authors will bring their biases and personalities to their work, intentionally or not. In this case, I am trying to give what is, in many places, an openly personal account of the story. You have been warned!

Human germline genome editing invokes many troubling, tricky, and deep general questions. But I am an American lawyer by training. We like looking at cases and working our way from specific examples to broader laws, principles, guidelines, or even rules of thumb. All settings are different, but they provide the opportunity to see consequences and concerns evoked in the real world that might be missed in the solitude of a scholar’s study or even in the busy hum of an engaged classroom. The Dr. He affair puts the many concerns about human germline genome editing—and many other forms of assisted reproduction, as well as other human interventions we humans make in ourselves—into a concrete setting. And it tells a fascinating, unnerving, and still unclear story. I hope you enjoy reading about it as much as I enjoyed writing about it. SL

Excerpted from CRISPR People: The Science and Ethics of Editing Humans by Henry T. Greely (BA ’74). Reprinted with permission from the MIT PRESS. Copyright 2021.