Revised CRISPR Gene Editing Technology Reduces “Off-Target” Effects

CRISPR-Cas9 gene editing technology has profoundly affected biological research. Relative to previous gene editing techniques, CRISPR-Cas9 allows genes to be edited with remarkable ease and accuracy (NEJM JW Gen Med Jun 15 2015 and Nature 2015; 520:186). However, because even CRISPR's accuracy is not perfect and “off-target” effects cause unwanted changes in other genes, some skeptics predicted that the technique would never be usable to treat human disease.

An international team now reports a modification of the technique that greatly improves its accuracy in human cells. The modification eliminated virtually all off-target effects when multiple different genes were targeted, including several genes whose structure was predicted to increase…