The popular new gene editing tool, CRISPR-Cas9, is not as precise as some have thought: undesired DNA deletions and rearrangements can slip through undetected.
These changes, seen before in CRISPR and other gene editing tools, could hamper development of reliable therapies and confuse interpretation of results. “I do think this has been underappreciated by the field,” noted Patrick Hsu, bioengineer at the Salk Institute in La Jolla, California.
When CRISPR’s Cas9 enzyme cuts DNA at a target site, the cell begins to repair itself—sometimes DNA segments are deleted or shifted, or unrelated DNA bits are included, since the cell doesn’t know what bits are adjacent. Large deletions and complex rearrangements have shown up in experiments with DNA cutting techniques, but not with DNA switching or turning genes on or off, and not with targeting RNA.
Genetic engineering firms are actively looking for deletions, but CRISPR should still be used, said James Haber of Brandeis University. More thorough analysis is needed when using CRISPR, he said, to “know whether your mutations are as you think they are.”
Source: Nature Biotechnology
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