Search-and-replace genome editing without double-stranded breaks or donor DNA.

Order of authorship in the original publication: Anzalone, Randolph, Davis....Liu.

Liu and colleagues modified the CRISPR tool to create the "prime editing" or precise genome editing technique. Working with human and mouse cells, the authors used a heavily modified Cas9 protein and the guide RNA. The new guide called "pegRNA" contains an RNA template with a reverse transcriptase which makes DNA for a new "desired/normal" DNA sequence from and on the blueprint carried in the pegRNA that is added to the genome at the abnormal / target location. With this new tool they performed 175 different edits, and as proof of principle, they created and then corrected the mutations that cause sicle cell anemia and Tay Sachs.

(Thanks to Juan Weiss for this reference and its interpretation.)