Two molecules which switch off CRISPR could be used to make gene editing therapies safer in the future. Harvard University’s Amit Choudhary and his colleagues said the molecules could stop CRISPR making unintended changes to DNA and potentially harming the individual.

The team analysed thousands of molecules for those which interfered with the enzyme’s ability to attach to DNA, a vital component of altering a gene. Two were found, and will be utilised to stop gene-editing “within minutes”. The molecules have been tested for toxicity, and don’t appear to disrupt any essential gene activity.

While larger anti-CRISPR proteins have previously been created, smaller inhibitors are more likely to act faster and without creating a reactionary immune response.