Researchers have developed a way to reduce the risks of a method that genetically engineers entire populations with unprecedented speed.

'Gene drives' are genetic changes, based on inserting parts of the CRISPR–Cas9 genome-editing system into a host genome, that spread through a population more rapidly than do normal mutations. Gene drives could be used to wipe out disease-carrying insects, for example, but could also spread uncontrollably in an ecosystem.

To reduce this risk, Kevin Esvelt and George Church of Harvard Medical School in Boston, Massachusetts, and their team inserted the bacterial DNA-cutting Cas9 enzyme into a piece of DNA external to the Saccharomyces cerevisiae yeast genome, and put the guide RNAs for directing Cas9 to a specific DNA sequence into the genome. This separation ensured that the gene drive would not spread exponentially if the strain was released into the wild.

Nature Biotech. (2015)