A panel of experts from the World Health Organization on Monday called on the world’s nations to place stronger limits on powerful methods of human gene editing.

Their recommendations, made after two years of deliberation, are aimed at preventing fraudulent scientific experiments on the human genome and ensuring that the correct use of gene editing techniques is available to the general public, especially people in developing countries and not only for the wealthy, is beneficial.

“I am very supportive,” said Dr. Leonard Zon, a gene therapy expert at Harvard University who wasn’t on the committee but called it a “thoughtful group.” The latest gene editing results are “impressive,” he said, and the committee’s recommendations are “very important for future therapy.”

The guidelines proposed by the WHO committee were largely triggered by the case of He Jiankui, a scientist in China who stunned the world in November 2018 when he announced that human embryonic DNA could be extracted using CRISPR, a technique that enables precise manipulation. having changed genes. Such changes meant that any changes in the genes would replicate in every cell in the embryo, including sperm and egg cells. And that meant that even if the changes were harmful rather than helpful, they would happen not just in babies born after gene editing, but in every generation their DNA was passed on to.

Dr. His goal was to modify babies’ DNA to make them genetically incapable of contracting HIV in their parents. A court in China found that he had forged ethics documents and misled subjects in the experiments who had failed to realize what his gene-editing experiment was made up of. In December 2019, he was sentenced to three years in prison.

The fact that such an experiment, known as germline editing, could take place raised the question of how to control gene editing and ensure that it is used for the benefit of humans.

The WHO standards state that Dr. He’s using germline editing was unacceptable and that it’s irresponsible to even consider it now. But other types of gene editing are a different story.

Scientists are already trying to do gene editing to correct the mutation that is causing sickle cell anemia. The changed gene would be in the blood-forming bone marrow cells of people with the disease, not in sperm or egg cells, so the changes would not be passed down through generations. But even this use of CRISPR raises other questions.

The WHO committee described a made-up scenario in which researchers from a wealthy country plan to conduct a clinical study on sickle cell gene editing in sub-Saharan Africa, where the disease is widespread. If the trial is successful, gene-editing treatment would be too expensive for all but a few citizens of the country in which it is to be tested.

Another hypothetical situation involves a gene-editing study to correct a gene mutation that causes Huntington’s disease, a progressive brain disease. People who inherit the mutated gene are absolutely certain to develop Huntington’s disease. If the gene-editing experiment is successful, it can save them from this terrible disease. And since the processing does not include sperm and eggs, the changes are not inheritable.

But it would take years, maybe decades, to find out if study participants whose genes were edited were protected from Huntington’s disease. Participants would not be exempt from the terrible fear that despite the gene editing, they would develop the deadly brain disease.

In one such scenario, the WHO group asked if there were any faster ways to assess the effectiveness of the treatment. It has also been suggested that the researchers consider the psychological distress of the participants who hope to be cured but are unsure.

But gene editing is there and holds huge promise, the committee said. The WHO has launched a registry of ongoing studies and says it already includes 156 experiments with genes not found in sperm or egg cells.

The WHO committee stressed that each country must have guidelines to ensure that research is carried out ethically and with adequate oversight, and that conditions are in place to ensure access and social justice. Since treatment costs will be very high, at least initially, the group’s goal must be to ensure that the benefits of gene editing are shared with people around the world.

“It’s not an easy challenge,” said Françoise Baylis, a committee member and medical ethics researcher at Dalhousie University in Halifax, Nova Scotia.