A committee of experts working with the World Health Organization on Monday called on countries around the world to place stronger limits on powerful methods of editing human genes.
Their recommendations, released after two years of deliberation, aim to eliminate spurious scientific experiments with the human genome and ensure that judicious use of gene editing techniques will have benefit the wider public, especially people in developing countries and not just the wealthy. .
Dr Leonard Zon, an expert in gene therapy at Harvard University who was not a member of the committee, said: “I’m very supportive, but call it a ‘thoughtful team’. The recent gene-editing results, he said, are “impressive,” and the committee’s recommendations will be “very important for future therapies.”
The guidelines proposed by the WHO committee were largely motivated by the case of He Jiankui, a scientist in China who shocked the world in November 2018 when he announced he had changed. Human embryo DNA using CRISPR, a technique that enables precise editing. of genes. Such changes mean that any change that occurs in the gene will be replicated in every cell of the embryo, including sperm and egg cells. And that means changes, even if they’re harmful instead of helpful, arise not just in the children born after the gene editing, but in every generation of their DNA being passed on. .
Dr. He’s goal is to change the DNA of babies to make them genetically invulnerable to HIV from their parents. A court in China determined he had forged ethics documents and misled experimental subjects who did not realize what his gene-editing experiment consisted of. He was sentenced to three years in prison in December 2019.
The fact that such an experiment, called germline editing, is possible raises the question of how to control gene editing and how to be sure it is used to yield benefits for humans.
WHO standards say that Dr He’s use of germline editing is unacceptable and that it is irresponsible to consider its use now. But other types of gene editing are a different story.
Scientists are trying to edit genes to correct the mutation that causes sickle cell disease. The edited gene will be in the blood-forming bone marrow cells of people with the disease, not in the sperm or egg cells, so the changes won’t be passed down through generations. But even using CRISPR raises other questions.
The WHO committee described an invented scenario in which researchers from a wealthy country wanted to conduct a clinical trial of sickle cell gene editing in sub-Saharan Africa, where the disease This is popular. If the trial is successful, the gene-editing treatment would be too expensive for all but very few citizens of the country where it was tested.
Another hypothetical scenario involves a gene-editing trial to correct a gene mutation that causes Huntington’s disease, a progressive brain disorder. People who inherit the mutated gene will inevitably develop Huntington’s disease. If the gene-editing experiment is successful, it could save them from that horrible disease. And because the editing doesn’t involve sperm and eggs, the changes won’t be inherited.
But it will take years, maybe even decades, to see if study participants with the edited gene are protected from Huntington’s disease. Participants will not escape the terrible fear that, despite the gene editing, they could still develop fatal brain disease.
In such a situation, the WHO team asked if there were more rapid ways to assess treatment effectiveness. It also suggests that researchers consider the psychological burden on participants who are hoping they’ll be cured but don’t know for sure.
However, gene editing is here to stay and holds great promise, the committee said. The WHO has begun registering studies in progress and says it has included 156 experiments involving genes that are not present in sperm or eggs.
The WHO committee stressed that each country must have guidelines in place to ensure research is conducted ethically and with appropriate oversight, and with the conditions in place to ensure access and equity. society. With treatment costs expected to be very high, at least first, the team said the goal must be to ensure that the benefits of gene editing are equitably accrued to people around the world.
“It was not an easy challenge,” said Françoise Baylis, a committee member who is a medical ethics researcher at Dalhousie University in Halifax, Nova Scotia.