Yet CRISPR has a dirty secret: there’s really no perfect way to deliver the “molecular scissors” safely into cells. Most methods currently rely on viruses: the DNA that encodes the CRISPR machinery is spliced into a “viral vector” then injected into the troubled tissue.

That’s all well and good for diseases that affect blood and muscle. But for destinations buried deep within the body, delivery becomes a serious issue.

Yin’s workaround wasn’t ideal: he shot two milliliters of solution containing the CRISPR machinery into the mice’s veins using incredibly high pressure. The human equivalent? Your entire blood volume, injected in just five minutes.