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In less than a decade since its adaptation to a genome-editing technique, CRISPR-Cas9 has been used on lab animals and cells around the world, as well on human cells that are already being tested in clinical trials to treat disease. Limitations such as off-target edits are widely acknowledged by CRISPR users, and researchers have been working to minimize them with tweaks to the method.
Adding to the list of issues that can occur with CRISPR, a team of researchers now reports a high frequency of unwanted duplications while engineering genetic insertions in mice. Worryingly to the scientists, the insertions couldn’t be detected using standard PCR analysis. The findings were published last week (February 12) in Science Advances.
“[This paper] is another cautionary tale about the use of CRISPR-Cas9–based gene editing for [knock-in] purposes,” remarks Ed Bolt, a molecular biologist at the University of Nottingham who wasn’t ...
