CRISPR-Cas9 revolutionized biology and healthcare. It hijacks the bacterial immune defense system to precisely edit a genome. But the method isn’t perfect. It can insert unwanted DNA sequences, delete segments entirely, and mistakenly mutate nontarget genes.
Research published in Science Advances today (July 1) reports that an alternative “soft CRISPR” called CRISPR-Nickase can efficiently and safely edit DNA.
CRISPR-Nickase leverages the fact that humans have two copies of each gene—one from each parent. Cas9, the molecular scissors that excise target genes, has two active sites that severs each copy. Nickase is a mutant of Cas9 with one site deactivated, so it just clips one.
Single cuts are useful when only one version of the gene is defective, a common occurrence in many genetic disorders. CRISPR-Nickase can remove the faulty copy, and the cell’s own DNA repair machinery can then copy the normal version in its place. This differs from traditional ...
