GM Watch: CRISPR spin-off causes unintended mutations in DNA
The past few years have seen a large number of research articles showing that the CRISPR gene-editing tool, designed to make a double-strand break in the DNA in a targeted location, may also cause many unintended mutations (damage to DNA).
Genetic engineers have tried to get around this problem by adapting the CRISPR gene-editing tool so that it no longer makes a double-strand break in the DNA. One adaptation consists of piggybacking onto the CRISPR tool an enzyme that changes individual DNA bases (so called “base editing”).
Base editing has been touted as a way of introducing changes in genes while avoiding the unintended effects, such as large deletions or rearrangements, which can arise from DNA repair processes following the usual CRISPR-induced double-strand DNA break.
However, two new papers (see references below) published in Science show that CRISPR base editing introduces more unwanted mutations than expected in mouse embryos and rice plants. The mistakes occurred in places where the editing tool wasn’t supposed to make changes. Another tested base editor did not make the undesirable edits.