Is CRISPR as Accurate as We Think?

CRISPR has been the talk of the medicine world for a while because of its incredible accuracy for gene editing. The hope is that CRISPR will cure genetic diseases and end all suffering caused by them. Companies have been pouring money into the potential that this technology holds. But a new study has suggested that it may not be as precise as we think.

The study published in Nature Biotechnology set out to test the accuracy of the Cas9 protein. Because this technology has the potential to aide in disease treatment development, among other things, it is important to make sure that it actually is safe for human trials.

This protein acts essentially like molecular scissors cutting a particular piece of DNA. The thing about the Cas9 protein is that is can remain active for several hours and sometimes several weeks in the body. So, there is the possibility that it will cut and paste other segments of DNA, or cut and paste the same segment of DNA over and over again.

To study this possibility, they looked at segments of embryonic stem cell DNA in mice and humans. They payed close attention to the areas that had been cut by Cas9. They found that it did in fact continue to cut and paste the same segment of DNA over and over, and that there were significant areas around the cut site where DNA had been removed, rearranged or inverted. This poses some possible problems as DNA that is removed improperly, rearranged or inverted, can become detrimental, sometimes causing disease.

Fortunately, Cas9 is not the only CRISPR associated protein, and there are other ways to edit DNA without cutting it. It has also been suggested that it might be possible to isolate the cells that need to be altered and only reinsert them when we are certain they have been correctly edited.

There is also the idea of a “CRISPR kill switch”, where the protein can be turned off. Three anti-CRISPR protein families were discovered in 2016, and researchers said that they are able to temporarily suspend the gene-editing activity. Temporary suspension is a good start and the researchers from University of Toronto and University of Massachusetts Medical Centre believe there may be more proteins to be discovered that have stronger effects.

It might seem like the possibilities that CRIPSR allows are endless, but there are also many questions that still need to be answered before we see this technology in regular use.


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