The scientists of seven nations have called for a halt to gene-editing experiments seeking to alter heritable traits in human babies. The declaration, published in Nature journal as a commentary, comes in response to Chinese scientist He Jiankui’s recent announcement that he had CRISPR-edited the genetics of two twins to make them resistant to HIV. Jiankui said that his decision was an ethical form of gene therapy, and not akin to “designer babies”.

The declaration, authored among others by two of the primary inventors of CRISPR, states that numerous warnings coming out of gene-editing conferences have clearly not been sufficiently taken up, and have failed to prevent ethical breaches of judgment. It also argues for the creation of an international governing body to oversee the application of CRISPR in future.

The moratorium calls for a temporary end to experiments involving sperm, eggs and embryos, and designed to result in pregnancy. It would not cover experiments not resulting in a birth, or gene-editing for therapeutic purposes in a patient’s non-germline cells, as these changes would not be heritable.

Director of the US National Institutes of Health Francis Collins has supported the halt, making it clear the US government was aligned with that resolve. He added: “What we’re talking about here is one of the most fundamental moments of decision about the application of science to something of enormous societal consequence. Are we going to cross the line toward redesigning ourselves?”