The gene-editing technology adapted for genome editing in the early 2010s that uses the Cas9 enzyme is CRISPR.
CRISPR is based on a bacterial immune defense system. In nature, bacteria store fragments of viral DNA in CRISPR sequences; when the virus returns, guide RNA helps the Cas9 protein recognize and cut matching genetic material. Researchers repurposed this system so guide RNA can direct Cas9 to a chosen location in DNA.
A landmark 2012 study by Jennifer Doudna and Emmanuelle Charpentier showed that CRISPR-Cas9 could be programmed to cut DNA. Work published in 2013 demonstrated genome editing in mammalian cells, accelerating research in medicine, agriculture, and biotechnology.
CRISPR is often confused with RNA interference, which mainly reduces gene activity by targeting RNA rather than cutting DNA. TALENs and zinc-finger nucleases also edit DNA, but they use engineered DNA-binding proteins instead of CRISPR’s guide-RNA approach.