Cas9 does not edit DNA, it cleaves DNA. What happens afterwards is up to the cell. The hype machine has ignored this fact. One of my favorite George Church quo

Cas9 does not edit DNA, it cleaves DNA. What happens afterwards is up to the cell. The hype machine has ignored this fact. One of my favorite George Church quotes: "CRISPR: some call it genome editing. I call it genome vandalism". Base Editors can actually edit DNA, but only single bases at a time. http://www.sciencemag.org/news/2017/10/novel-crispr-derived-base-editors-surgically-alter-dna-or-rna-offering-new-ways-fix http://www.sciencemag.org/news/2017/10/novel-crispr-derived-... There's a big prize waiting for the person who can harness DNA repair pathways in conjunction with Cas9 to make precise, multi-base DNA edits. Lots of folks are working on that now.