Ever since the now Nobel-winning discovery of CRISPR genome editing in 2012, scientists have been racing to improve on its DNA-targeting-and-cutting action. A huge step forward came in 2016, with the invention of base editing, and another with prime editing in 2019, both from the lab of David Liu, of the Broad Institute of MIT and Harvard. The advances made it possible to precisely slice open a double-strand of DNA and change the sequence — swap out a nucleotide for another, or add or subtract a few in one go. But when faced with making bigger deletions, anything over 100 base pairs, even these shiny new tools weren’t up to the task.
Now, two teams of scientists have independently developed even newer versions of prime editing that can precisely cut out up to 10,000 base pairs at a time. One of the groups also used their method to cure mice of an inherited liver disorder.