Of all the new ideas, scientific breakthroughs, and transformative technologies that I’ve written about, CRISPR-CAS-9 gene editing has the chance to make the biggest impact; saving the world several times over by eradicating diseases and creating more sustainable crops and biofuels. It also pales in comparison to a new gene editing technique that may very well have the potential to cure almost all diseases.
As Wired explains, “The system, which [David] Liu’s lab has dubbed ‘prime editing,’ can for the first time make virtually any alteration—additions, deletions, swapping any single letter for any other—without severing the DNA double helix. “If Crispr-Cas9 is like scissors and base editors are like pencils, then you can think of prime editors to be like word processors,” Liu told reporters in a press briefing.
Why is that a big deal? Because with such fine-tuned command of the genetic code, prime editing could, according to Liu’s calculations, correct around 89 percent of the mutations that cause heritable human diseases. Working in human cell cultures, his lab has already used prime editors to fix the genetic glitches that cause sickle cell anemia, cystic fibrosis, and Tay-Sachs disease. Those are just three of more than 175 edits the group unveiled…”
Considering the challenges associated with gene-editing – the precision required, the specific instructions needed, the blind faith in the cell’s machinery to follow the instructions and make the required edits – it’s no surprise that if often doesn’t go according to plan. For all its promise, it’s far from full-proof. Prime editing on the other hand, is light years beyond CAS-9’s capabilities. As David Liu put it, we’re talking about the difference between crudely using scissors to make edits and using Microsoft word to cut and paste.
Here’s exactly how it works:
“prime editor is a little different. Its enzyme is actually two that have been fused together—a molecule that acts like a scalpel combined with something called a reverse transcriptase, which converts RNA into DNA. His RNA guide is a little different too: It not only finds the DNA in need of fixing, but also carries a copy of the edit to be made. When it locates its target DNA, it makes a little nick, and the reverse transcriptase starts adding the corrected sequence of DNA letter by letter, like the strikers on a typewriter. The result is two redundant flaps of DNA—the original and the edited strand. Then the cell’s DNA repair machinery swoops in to cut away the original (marked as it is with that little nick), permanently installing the desired edit.”
Now, prime editing isn’t perfect. The size of these larger molecules may be difficult to deliver into the body. Mistakes can still happen. But at the very least it shows us what’s possible. Shows us that when it comes to gene editing we’ve only just begun to scratch the surface of what may be possible.
Is Prime Editing the Greatest Idea Ever?
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