A Ban, Not a Moratorium, on Human Embryo Modification

A twin birth in China last October raised ominous questions. The baby girls had been genetically edited as embryos, with the untested methods providing no confidence in healthy outcomes. The subsequent fallout has been confusing: a blue-ribbon group of scientists and ethicists sent a letter to the Secretary of Health and Human Services in late April recommending a moratorium, following a similar call in the scientific journal Nature. In both cases, the door was left open to clinical use if and when relevant stakeholders are satisfied it should proceed. And if the federal government won’t fund it, the tax-payer supported California Institute of Regenerative Medicine (CIRM) could.

When the relevant science (developmental biology) is considered, however, it becomes evident that embryo modification cannot proceed safely. Time-buying measures such as moratoria are simply strategies to deny this reality and enable its eventual implementation. But the question of whether embryos can be safely engineered has long been settled: they cannot. This is clear from experiments on animal embryos, where altered genes are seen to behave in unpredicted ways, and in human...