But CRISPR editing — at least as a therapeutic technique in people — has turned out to be more difficult than initially thought. Researchers have documented ways that Cas9, one of the enzymes used in CRISPR gene editing, could trigger immune responses, or cause accidental changes to the genome that would be permanent. RNA editing, by contrast, could allow clinicians to make temporary fixes that eliminate mutations in proteins, halt their production or change the way that they work in specific organs and tissues. Because cells quickly degrade unused RNAs, any errors introduced by a therapy would be washed out, rather than staying with a person forever.
Making changes to the molecular messengers that create proteins might offer flexible therapies for cancer, pain or high cholesterol, in addition to genetic disorders.