HONG KONG — The Chinese government said Thursday it had halted research that allegedly led to the births of the world’s first gene-edited babies, as the organizers of an international summit on human genome editing made clear that such research should not have been done and that, for now, similar attempts should not be made.

“We continue to believe that proceeding with any clinical use of germline editing remains irresponsible at this time,” the 14-member organizing committee said in a statement, referring to the editing of sperm, eggs, or early embryos in ways that create changes that would be inherited by future generations.

Still, much as they did after the original human genome editing summit, held in 2015 in Washington, D.C., the organizers left the door open to one day sanctioning germline editing to prevent or cure certain inherited diseases if the technical, ethical, and regulatory challenges can be met.

advertisement

As of now, though, germline editing “poses risks that remain difficult to evaluate,” the committee said.

Meanwhile, the Associated Press reported that China’s Vice Minister of Science and Technology, Xu Nanping, told a state television network that his ministry is strongly opposed to the efforts that reportedly produced twin girls born earlier this month in China. Xu called the team’s actions illegal and unacceptable and said an investigation had been ordered, though he made no mention of specific actions taken.

advertisement

The experiment “crossed the line of morality and ethics adhered to by the academic community and was shocking and unacceptable,” Xu said.

One key difference from the 2015 statement of the summit’s organizing committee: there was no call for the necessity of “broad societal consensus” before germline editing could go forward. When asked about that in Hong Kong, bioethicist and organizing committee member R. Alta Charo of the University of Wisconsin said such an accord is unlikely given how different countries view germline editing.

“Countries that wish to go forward should do it carefully,” Charo said.

The summit closed as experts were grappling with the failure of international guidelines and ethical norms to prevent a researcher, He Jiankui, from allegedly starting pregnancies with edited embryos. Until He announced his project — work that has not been independently verified and published in an academic journal — scientists had edited embryos only for research purposes, never to start pregnancies that could result in births.

On the eve of the summit, however, He, who is based in Shenzhen, rocked the global scientific community by claiming to have helped make a set of twin girls whose genomes were edited as embryos. What’s more, on Wednesday in Hong Kong, He defended his work against almost universal condemnation and said that he had started another pregnancy with edited embryos.

Scientists in Hong Kong were also reflecting on the lack of regulatory enforcement in many parts of the world to ensure that rogue scientists don’t pursue this type of research on their own. It’s become a real possibility as CRISPR — the easy-to-use genome-editing tool He used in his work — as been embraced by scientists around the globe. (Germline editing remains illegal in the United States.)

“I think it’s safe to say that we have reason to be concerned [that other CRISPR pregnancies may be underway] and you can imagine almost anything,” said David Baltimore of the California Institute of Technology, the chair of the committee that organized the Hong Kong conference. “It is a serious concern, and if any people working in the field get an indication that there are other labs moving ahead in an irresponsible fashion, it is very important they let authorities know that.”

Baltimore added: “We failed to prevent this, though I don’t see how we could have. He showed that if you want to be surreptitious, you can go a surprisingly long way.”

As STAT reported this week, He had told at least one U.S. researcher in confidence what he was up to a year ago. Though the University of California, Berkeley, scientist urged He not to proceed, that researcher never told colleagues or authorities about He’s efforts.

In its statement, the organizing committee criticized He’s research — though it never referred to him by name — on multiple fronts. It took issue, for example, with the gene He targeted in the embryos. He tried to disable a gene called CCR5 to protect the girls against HIV infection, whereas other researchers envision one day using germline editing to prevent or cure genetic diseases.

The committee also criticized the “poorly designed study protocol,” inadequate protect for the study’s participants, and lack of transparency in the “development, review, and conduct of the clinical procedures.”

Genome editing using CRISPR is still very new and carries risks — including the possibility of cutting DNA in unanticipated places, which could damage important genes or lead to the development of cancer. And disabling genes can have other unintended consequences: disabling the CCR5 gene, for example, could make people more susceptible to viruses such as West Nile, or even influenza.

The committee called for an independent evaluation to verify He’s claims and “ascertain whether the claimed DNA modifications have occurred.” Even if the modifications are verified, it added, “the procedure was irresponsible and failed to conform with international norms.”

Although scientists right now cannot fully appreciate all the risks involved with germline editing, the committee said, such a practice could one day be acceptable. Because of that, the committee called on the scientific community to define what a pathway to clinical trials should look like. In effect, they are saying that scientists need to outline what preclinical evidence — including the demonstrated accuracy of the editing strategy — will be required before trials can start and how reviewers can assess the skills of the clinicians intending to lead such trials.

Any future trials, the committee said, will require “strict independent oversight, a compelling medical need, an absence of reasonable alternatives, a plan for long-term follow-up, and attention to societal effects.”