Can We Cure Genetic Diseases Without Slipping Into Eugenics?

On April 18, scientists at Sun Yat-sen University in Guangdong, China, published an article in the obscure open-access journal Protein & Cell documenting their attempt at using an experimental new method of gene therapy on human embryos. Although the scientific significance of the results remains open to question, culturally the article is a landmark, for it has reanimated the age-old debate over human genetic improvement.

The Chinese scientists attempted to correct a mutation in the beta-globin gene, which encodes a crucial blood protein. Mutations in this gene lead to a variety of serious blood diseases. But the experiments failed. Although theoretically the new method, known as CRISPR (short for “clustered regularly spaced short palindromic repeats”) is extremely precise, in practice it often produces “off-target” mutations. In plain English, it makes a lot of changes in unintended locations, like what often happens when you hit “search/replace all” in a word-processing document. The principal conclusion from the paper is that the technique is still a long way from being reliable enough for the clinic. Nevertheless, the science media and pundits pounced on...