CRISPR Rules When It Obeys the CRISPR Rules

When the gene-editing system known as CRISPR is used, DNA breaks occur fairly reliably, but not DNA repairs—specifically, the repairs that are supposed to insert synthetic donor DNA. But repairs may be more likely to “stick,” say Johns Hopkins scientists, if donor DNA is designed properly.The scientists suggest that homology-directed repair, the usual mechanism for knockin of new genetic material, is more efficient if a few design rules are followed. In a nutshell, the rules ar