A Chinese scientist has produced twins using the powerful gene-editing technology. This is pointless, dangerous and unethical
The Crispr/Cas9 technique of editing DNA is, by the standards of earlier methods, astonishingly quick and easy. It is not entirely reliable or accurate, but it places enormous potential power in the hands of ordinary scientists. It is also internationally widespread, and beyond the control of any single nation now. So reckless and unethical experiments were only to be expected; nonetheless, last week’s announcement by a Chinese scientist that he had altered the germlines of twin girls to modify a gene involved in the transmission of HIV was a profoundly worrying one, for several reasons.
The most important is that there is no medical reason for what he did. There is a vitally important difference between editing the genes which are present in a body and those which are present in sperm or eggs. With the first kind of modifications, the effects die with the bearer. With the second, they are passed, like mutations, down into future generations. Of course such mutations might in theory be entirely beneficial. But scientists don’t at the moment have nearly enough knowledge to judge whether this is true or even probable in practice. They’d need to know at least how any particular modified gene will perform over a lifetime, and, ideally, what effects it might have in subsequent generations.