CRISPR (Credit: Ernesto del Aguila III, NHGRI)

The gene editing technology CRISPR is pretty much king right now, after being branded as “revolutionary” and “world-changing” it’s hard to imagine anything standing in its way. 

Well, last summer a letter appeared in a scientific journal doing exactly that and challenging these claims. Researchers found that when they used CRISPR to cure blindness in mice, it had resulted in not just a few but more than a thousand unintended changes. These changes were not detectable using common methods for checking for off-target effects. As a result, the authors hit back at CRISPR, reinforcing that it needed significant fine-tuning before it was ready to cure disease in people. It was no surprise that stocks fell, and the scientific community panicked. 

Dynamic DNA Dance Identified with New CRISPR/Cas9-Based Labelling

But, a new paper published as a preprint on the website bioRxiv extended an olive branch to CRISPR. The paper lent support to the assertion that the initial mouse study was more than just a false alarm. In an effort to eradicate such claims, scientists at the Wellcome Sanger Institute in Britain recreated the study and found that there wasn’t much to be concerned about. To prove this even further, during their recreation they used far more rigorous controls for the sake of accuracy. The mice that had CRISPR used on them didn’t have a significant difference in gene mutations than those that didn’t receive the treatment. 

There will always be the possibility of unintended effects when developing CRISPR therapy. Last month, a study found that CRISPR triggered an immune response in human cells, but it does suggest that it’s not as big a concern as last summer’s paper proposed. 

“This work should support further efforts to develop CRISPR-Cas9 as a therapeutic tool,” they added.