How Editing RNA—Not DNA—Could Cure Disease in the Future

DNA is the code of life, and so advances that allow us to edit that code have unlocked vast potential, from simply editing away the buggy code of disease, to engineering animals that don’t spread illness, to, maybe one day in a distant future, creating so-called designer babies. But editing another essential molecular component of our biology—RNA, the messenger used by cells to turns DNA instructions into proteins—also holds great promise.

A slew of recent high-profile discoveries have focused on pairing the buzzy genetic engineering tool, CRISPR, with RNA editing. RNA is a sort of middleman that turns genetic instructions from DNA into proteins. Editing RNA could allow scientists to tweak how genes are expressed without making permanent changes to the genome itself—thus avoiding one of the scarier aspects of genetic engineering, because you’d be interfering with DNA’s instructions rather than editing DNA itself. RNA is ephemeral, which means changes to it could be reversed. And in some diseases, like a form of muscular dystrophy called myotonic dystrophy, mutant RNA is actually the root of the problem.

In October...