A new experimental version of CRISPR could help fix genes rather than disable them using transposons, or “jumping genes”. This could help move the current “find and delete” purpose of CRISPR to the more useful “find and replace” one.

The usual CRISPR form adds the Cas9 protein to a cell, alongside some guide RNA. The protein finds the gene sequence that matches the RNA and cuts the gene at that point. When the cell repairs the cut ends, some DNA is lost, usually resulting in the gene being disabled. 

The new approach to CRISPR, devised by Feng Zhang of MIT, uses genes which copy and past themselves from one part of the genome to another using transposases, a type of enzyme. More than half of the human genome is made up of these defunct jumping genes.

It was recently found that certain CRISPR systems in bacteria have been hijacked by Tn-7 jumping genes, using Cas12k to find specific sequences and insert jumping genes into the site. Zhang’s team used this system to insert long reads of DNA into specific sites in E. coli bacteria. This method worked around 80% of the time.