CRISPR Is Not Accurate Enough to Save Us Yet

Image: Global Archive/Flickr
Scientists are at odds over a study that says gene editing comes with thousands of unwanted mutations.

By Mallory Locklear | MOTHERBOARD

The gene-editing tool CRISPR is everywhere these days. Scientists are using it to try and fight cancer and treat muscular dystrophy, companies are using it in agriculture, and TV executives are even writing it into shows.

And it’s ubiquity isn’t surprising because CRISPR is one of the biggest scientific discoveries of our time. It tremendously improves upon earlier gene-editing techniques because it’s fast, cheap, and accurate. Or so we thought. A new study published last week in Nature Methods found that CRISPR might not be as precise as researchers believed it to be. But not everyone agrees.

In the study, researchers were using a strain of mice that had mutations causing early onset retinal degeneration—a disorder that blinded the mice. Using CRISPR, the researchers were able to snip out and correct a mutation in a particular gene to restore the mice’s vision.

But the scientists were curious about what are known as „off-target“ effects, or secondary mutations caused by CRISPR that occur away from the intended genetic target. So, they compared the DNA from two CRISPR-treated mice to that of a mouse which hadn’t received the gene editing. They found a surprisingly large number of differences. Namely, the CRISPR-treated mice had around 1400 small off-target mutations and over 100 more considerable genetic alterations.

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