We strongly support Eric Lander and colleagues’ call for an international moratorium on clinical uses of human germline editing. We also welcome the proposed process that nations could consider in the future to determine whether necessary conditions to lift the moratorium have been met.

Adopt a moratorium on heritable genome editing

This is a crucial moment in the history of science: a new technology offers the potential to rewrite the script of human life. We think that human gene editing for reproductive purposes carries very serious consequences — social, ethical, philosophical and theological. Such great consequences deserve deep reflection. A substantive debate about benefits and risks that provides opportunities for multiple segments of the world’s diverse population to take part has not yet happened. Societies, after those deeper discussions, might decide this is a line that should not be crossed. It would be unwise and unethical for the scientific community to foreclose that possibility.

There are significant reasons to support a moratorium at the present time. As Lander and colleagues note, the risks currently far outweigh the benefits, given the serious and unquantifiable safety issues, ethical concerns and lack of sufficiently compelling medical applications. Although some extremely rare medical scenarios could exist in which germline editing might be the best or only option, those arguments must be balanced against the many other considerations.

Gene editing has enormous potential in other applications to advance science and save lives. The US National Institutes of Health is prohibited from supporting the use of germline gene-editing technologies in human embryos, but we consider research on therapeutic uses of gene editing in somatic cells — in diseases such as sickle-cell anaemia and muscular dystrophy — to be among our highest priorities.