The CRISPR gene editing system holds tremendous promise. It has already revolutionized biomedical research by making gene editing a straightforward process. It involves using a guide RNA molecule that has a unique sequence, which matches with a target location in genomic DNA. This guide RNA brings an enzyme called Cas9 to that genetic location, where Cas9 makes a cut in the DNA. Scientists have been modifying and improving on the CRISPR technique since it was created. Many of those improvements are related to the Cas9 enzyme, and ensuring that it makes the proper cut in the correct place.