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Editing tool is found to be prone to making off-target “nicks” in DNA

The gene-editing tool known as CRISPR-Cas12a or Cpf1 has been viewed as a better choice than other Cas editing tools because it was believed to be more precise and less prone to making off-target cuts in DNA.

But a new paper shows that Cpf1 is not as clean or specific as touted. The researchers employed in vitro assays using a vast collection of synthesized DNA molecules containing variations on the editing site sequence. They found that Cpf1 was highly prone to making off-target single-strand cuts, or “nicks”, in the double-stranded DNA molecules. Off-target double-strand DNA cuts were also found, albeit at a lower frequency than the single-strand nicks.