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 the story, and for a while “#CRISPR” was trending on Twitter.
CRISPR is the fastest, easiest, and most promising of several new methods known collectively as “gene editing.” Using them, scientists can edit the individual letters of the DNA code, almost as easily as a copy editor would delete, a stray comma or correct a speling error. Advocates wax enthusiastic about its promise for correcting mutations for serious genetic diseases like cystic fibrosis and sickle-cell anemia. Other applications might include editing HIV out of someone’s genome or lowering genetic risks of heart disease or cancer. Indeed, every week brings new applications: CRISPR is turning out to be an extraordinarily versatile technique, applicable to many fields of biomedical research. I’m pretty immune to biomedical hype, but gene editing has the marks of a genuine watershed moment in biotechnology. Once the kinks are worked out, CRISPR seems likely to change the way biologists do experiments, much as the circular saw changed how carpenters built houses.
The timing of the paper was provocative. It was submitted on March 30 and accepted on April 1; formal peer review was cursory at best. Two weeks before, scientists in the United States and Europe had called for a moratorium on experiments using CRISPR on human “germ-line” tissue (eggs, sperm, and embryos), which pass alterations on to one’s descendants, in contrast to the “somatic” cells that compose the rest of the body. The embryos in the Chinese experiments were not implanted and in fact could not have become humans: They were the unviable, discarded products of in vitro fertilization. Still, the paper was a sensational flouting of the Westerners’ call for restraint. It was hard not to read its publication as an East Asian Bronx cheer.