Cracking the CRISPR Code

Scientists at the Francis Crick Institute have discovered a set of simple rules that determine the precision of CRISPR/Cas9 genome editing in human cells. These rules, published in Molecular Cell, could help to improve the efficiency and safety of genome editing in both the lab and the clinic. Despite the wide use of the CRISPR system, rational application of the technology has been hindered by the assumption that the outcome of genome editing is unpredictable, resulting in random deletions or insertions of DNA regions at the target site. Before CRISPR can be safely applied in the clinic, scientists need to make sure that they can reliably predict precisely how DNA will be modified.
"Until now, editing genes with CRISPR has involved a lot of guesswork, frustration and trial and error," says Crick group leader Paola Scaffidi, who led the study. "The effects of CRISPR were thought to be unpredictable and seemingly random, but by analyzing hundreds of edits we were shocked to find that there are actually simple, predictable patterns behind it all. This will fundamentally change the way we use CRISPR, allowing us to study gene function with greater precision and significantly accelerating our science."