Scientists call for global moratorium on gene editing of embryos

Leading scientists have called for a global moratorium on the use of powerful DNA editing tools to make genetically modified children.

The move is intended to send a clear signal to maverick researchers, and the scientific community more broadly, that any attempt to rewrite the DNA of sperm, eggs or embryos destined for live births is not acceptable.

Beyond a formal freeze on any such work, the experts want countries to register and declare any plans that scientists may put forward in the future, and have these discussed through an international body, potentially run by the World Health Organisation.

Alongside technical debates about the possible benefits of creating genetically modified babies, the scientists said no decisions should be made to go ahead without broad public support.

“What we want to see are wise and open decisions,” said Eric Lander, founding director of the Broad Institute of MIT and Harvard in Cambridge, Massachusetts. “We want to make sure that countries don’t do things secretly, that we declare what we’re thinking, discuss it openly, and be prepared for debate and disagreement.”

Lander, who co-chaired Barack Obama’s council of advisors on science and technology, calls for the moratorium with 16 other experts in the journal Nature. Emmanuelle Charpentier and Feng Zhang, who helped discover and develop the most common gene editing tool, Crispr, contributed to the article.

Crispr, or to give it its full name, Crispr-Cas9, allows scientists to precisely target and edit pieces of the genome. Crispr is a guide molecule made of RNA, that allows a specific site of interest on the DNA double helix to be targeted. The RNA molecule is attached to Cas9, a bacterial enzyme that works as a pair of “molecular scissors” to cut the DNA at the exact point required. This allows scientists to cut, paste and delete single letters of genetic code. 

The call comes four months after a Chinese researcher announced the birth of twin girls, Lulu and Nana, who had their DNA rewritten while still embryos in a bid to make them resistant to HIV, the virus that causes Aids. He Jiankui was sacked by the Southern University of Science and Technology in Shenzhen after he was found to have broken Chinese regulations. He was heavily criticised for what many experts viewed as a reckless and unethical experiment.

Gene editing tools like Crispr allow scientists to make precise changes to the DNA code. Many researchers believe it could lead to a revolution in the treatment of medical conditions such as muscular dystrophy and cystic fibrosis, for example, by correcting faulty genes in muscles and lungs respectively.

The same approach could potentially be used to correct genetic defects in embryos, a process called “germline editing”, but doing so is expected to help people only rarely. Most children with severe genetic diseases are born without anyone knowing they are at risk. And when the risk is known about, other options exist such as using donor eggs or sperm in IVF, screening embryos for mutations, or adoption.

In the case of Lulu and Nana, He tried to disable a gene called CCR5 in order to mimic a natural mutation that protects a small percentage of people from HIV. But scientists warn that too little is known about genes to make such changes safely, that other genes can be damaged in the process, and that the changes are passed on to future generations.

The call for a moratorium received strong backing from the US National Institute of Health. “We have to make the clearest possible statement that this is a path we are not ready to go down, not now, and potentially not ever,” the NIH director, Francis Collins, told the Guardian.

But others held back from supporting the call. One of the inventors of Crispr gene editing, Jennifer Doudna at the University of California, Berkeley, called for an effective moratorium in 2015, only to see it ignored by He and his colleagues. She now backs plans by the Royal Society and two US national academies to have regulations that bar heritable gene editing until scientific, technical and ethical questions are answered and there is a public consensus to proceed. “I prefer this to a moratorium which, to me, is of indefinite length and provides no pathway toward possible responsible use,” she said.

In an accompanying letter to Nature, the Royal Society, the US National Academies of Science and the US National Academy of Medicine said they shared Lander’s concerns, but they did not back the call for a moratorium.

“The Royal Society has been particularly reluctant to go down this path because of a concern that it might in some way slow down research that ultimately could be valuable,” Collins said. “They risk being seen as self-serving, as scientists who want to do science and don’t want to have others say: ‘No, for now, you shouldn’t’.

“We have not had the beginnings of a serious discussion about going down this path of modifying our own instruction book. Of all the things that science has made possible in the past several decades that would have massive consequences for humanity, this has to be top of the list,” he added.

“In this case, random bad actors will not ruin the world, the choices that nations make are what’s important,” Lander said. “We’re trying to plan the world we’re going to leave for our children. Is it a world where we’re deeply thoughtful about medical applications, and we’re using it in serious cases, or is it a world where we just have rampant commercial competition?”