By simply tweaking the natural Cas9 protein in a few different places—swapping out one amino acid for another—researchers, including Keith Joung from Harvard Medical School and Feng Zhang from MIT, have developed higher-fidelity versions of CRISPR that are less prone to off-target gene editing than the version nature evolved on its own. Finally, the dosage of CRISPR affects the likelihood of the genome being riddled with unintended mutations.
