A landmark meeting of scientists convened to debate the future of human gene editing has ruled out a ban on modifying human embryos that are destined to become people.

But the experts made clear that altering the DNA of human embryos for clinical purposes was unacceptable given the unknown risks today and noted that even the most compelling cases to use the procedure were limited.

The international summit in Washington was organised by the national academies of the US, UK and China to take stock of powerful new tools that can make precision changes to the code of life, by correcting, removing and adding DNA to an organism’s genome.

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One gene editing technique, known as Crispr-Cas9, is so simple to use that the number of experiments using it in labs around the world has increased dramatically in the past two years. The rapid adoption of the powerful tool prompted scientists to gather at the summit and thrash out guidelines for its responsible use in the future.

The statement from the organising committee follows three days of discussion among scientists, lawyers and ethics experts, who considered: the potential for therapies in adult tissues, such as blood cells and muscles; the ethics of modifying embryos for research only; and most importantly whether altering the DNA of human embryos to prevent inherited diseases was acceptable and useful.

Earlier this year, the UK parliament voted to allow a procedure called mitochondrial transfer in human embryos, an experimental therapy that aims to prevent rare genetic diseases from being passed on from mother to child. The law forbids any other form of genetic modification of embryos, unless it is for research only, in which case the donated embryos must be destroyed after 14 days.

In principle, gene editing could be used to prevent couples from passing on a genetic disorder to their children. If the genetic fault is known early on, the couple could have IVF to create embryos and have the faulty genes corrected at that stage. But so-called germline therapy affects not only the unborn child, but his or her future generations. If the procedure causes unexpected harm, undoing the damage may not be straightforward.

Outlining their position, the summit committee said: “It would be irresponsible to proceed with any clinical use of germline editing unless and until the relevant safety and efficacy issues have been resolved, based on appropriate understanding and balancing of risks, potential benefits, and alternatives, and there is broad societal consensus about the appropriateness of the proposed application.”

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Critics of germline therapy argue that any couple at risk of passing on a genetic disorder to their children could avoid the outcome by going through IVF and having their embryos screened for problematic genes, by using donated sperm or eggs, or adopting. Future uses could see germline editing used to lower people’s chances of developing Alzheimer’s disease and other conditions by removing high risk genes.

The committee recommended scientists push ahead with gene editing for other therapies that would not affect future generations. The tool may one day help scientists correct the genes that cause sickle-cell anaemia in blood cells, and improve the ability of the immune system to attack cancer cells. But even this work had potential dangers, the statement cautioned. “There is a need to understand the risks, such as inaccurate editing, and the potential benefits of each proposed genetic modification,” it says.

Paul Knoepfler, a cell biologist at the University of California, Davis, and author of the forthcoming GMO Sapiens: The Life-changing Science of Designer Babies, said that while he agreed with the need for more basic research and progress towards therapies in adult tissues, he hoped for a stronger line on changes to human embryos for clinical purposes.

“I’m disappointed that the organisers did not propose at least a temporary moratorium on germline human genetic modification,” he told the Guardian. “It’s not clear to me what the downside of a temporary moratorium would have been.

“Several of the organisers clearly and in some cases strongly advocated for a ‘pause’ in germline editing in the last few months. What changed? I don’t believe that stating that germline human editing attempts would be irresponsible – although I think that is true – is strong enough.”

The committee conceded that safety issues have not been well explored and that many countries have legal or regulatory bans on germline modification. But it added that the question of whether it should be allowed should be reconsidered at future meetings. “As scientific knowledge advances and societal views evolve, the clinical use of germline editing should be revisited on a regular basis,” the statement read.