A team of researchers led by Feng Zhang at the Broad Institute of MIT and Harvard and the McGovern Institute for Brain Research at MIT has uncovered the first programmable RNA-guided system in eukaryotes — organisms that include fungi, plants, and animals. In a study in Nature, the team describes how the system is based on a protein called Fanzor. They showed that Fanzor proteins use RNA as a guide to target DNA precisely, and that Fanzors can be reprogrammed to edit the genome of human cells. The compact Fanzor systems have the potential to be more easily delivered to cells and tissues as therapeutics than CRISPR/Cas systems, and further refinements to improve their targeting efficiency could make them a valuable new technology for human genome editing.