Researchers from Sun Yat-sen University, Guangzhou failed to selectively modify a single gene in unicellular human embryos using the CRISPR/Cas9 technology, noting many off-target mutations. The study received a lot of media and public attention (NYT, Nature, TIME), primarily because of ethical concerns about human genetic modification expressed earlier.

The authors seem to ignore the opinion of many scientists in the US, including the original developers of CRISPR/Cas9 technology, who called for a pause in all human germline gene editing studies until the risks and benefits can be accessed by the public and the research community. This shows that international research community currently lacks power to discourage potentially dangerous or ethically questionable research if national governments choose to support it. However, it is important that the paper was rejected by Nature and Science (and, possibly, other journals) in part due to ethical considerations and had to be published in a much less prestigious Chinese journal Protein & Cell. This is a reason for optimism: if Science, Nature and other high-impact journals can coordinate on this, they might be able to cooperate in others cases of research of concern, such as Gain-of-Function studies.

While some think that the study shows that CRISPR gene editing has a long way to go before it is ready for the use in humans, this seems unlikely to me. Previous studies in mice, and, more importantly, in monkeys were very successful (in case of monkeys “no off-target mutagenesis was detected”). It seems more likely that the failure of the Chinese study was caused by the defective embryos – in an attempt to mitigate ethical concerns, the researchers used tripronuclear zygotes, which can’t develop normally. It may turn out that normal human embryos are much easier to modify and, given that, according to Nature, there are at least 4 other Chinese groups working on similar problems, we may find this out sooner than we might want.