DNA editing tool CRISPR can cause serious genetic damage, scientists warn

A new study has revealed that gene editing tool, CRISPR-Cas9, can actually cause 100 times more damage than what was initially observed.

Short for Clustered Regularly Interspaced Short Palindromic Repeats, CRISPR is basically a molecular pair of scissors which can cut two strands (or bases) of DNA at a specific location in the genome and then either remove or insert additional DNA. This can have a number of medical applications and can cure most genetic diseases like sickle cell anaemia by deleting the genome altogether.

The study, conducted by researchers at the Wellcome Sanger Institute, showed that CRISPR could produce insertions and deletions (or indels) to the tune of thousands of bases. This would affect neighbouring genes and interfere with normal genetic operations.

Researchers clarify that the technology itself cannot be blamed; a sloppy repair job by the cell is what can cause this problem.

After CRISPR snips the genome, the cell will try and repair the ‘damage’ but it does not know where certain DNA bits are supposed to go. The cell may accidentally cut and paste hundreds or even thousands of base pairs that were not there to begin with.

Fortunately, the damage only seems to occur when CRISPR initially snips, leaving the cell open to try and repair the sequence.

The study explains that this type of damage may have gone unnoticed by previous research due to the fact that it never allowed that kind of damage to occur. Previous studies used several copies of the same sequence to test CRISPR’s mettle, so the possibility of damaging thousands of base pairs was mostly absent. It is only when longer and more varied strands of DNA are involved that these high-volume indels can occur.

This does not mean that the technology should be scrapped but the clinical repercussions of any possible damage should be explored and accounted for. However, there is a possibility that this discovery could put CRISPR temporarily on ice.

In 2012, biochemist Jennifer Doudna and microbiologist Emmanuelle Charpentier were the first to propose that the CRISPR-Cas9 tool could be programmed for genetic editing. That proposal is now considered as one of biology’s most important moments.