New CRISPR Technique Has the Potential to Eliminate Most Genetic Diseases

First of all, let’s make sure we’re all on the same page re: CRISPR.

At its core, CRISPR is a gene-editing tool that allows scientists to change the genetic blueprint of pretty much every living thing in existence. In fact, in the 10 years its development, the technology has been used to change DNA to make tomatoes more red, mushrooms that don’t spoil, and crops that resist insects.

It’s made up up two parts – a DNA slicing enzyme called Cas9 and a strand of guide RNA that tells it where to cut.

Other enzymes can direct it to do things, like turn off a gene, unzip the DNA a bit and knocking out one letter, things like that.

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Co-inventor and biochemist Jennifer Doudna explains,

“This technology operates efficiently in virtually all cell types of organisms in which it’s been tested.

It was really quite amazing how quickly it was possible to harness this technology once it was clear how it operated.”

For all of its (admittedly amazing) successes, until now, CRISPR has been better at breaking genetic code than it is had being able to replace a bad gene with a better one.

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But until now, programmers have struggled with getting the machine to install corrected DNA correctly, but recently Columbia MD/PhD candidate Andrew Anzalone thinks he might have come up with a way to fix that issue.

He thought, what if there was a way to both tell CRISPR where to make its changes and what edits to make, all on one molecule?

To find out, he joined the lab of chemist David Liu, who had recently developed a bunch of surgical CRISPR systems that he calls base editors. Together, they began to bring Anzalone’s idea to life, and they have been able to make any alteration – additions, deletions, swapping – without damaging or snipping the DNA double helix.

Liu explained in a press briefing,

“If Crispr-Cas9 is like scissors and base editors are like pencils, then you can think of prime editors to be like word processors.”

Everyone is excited about their invention because, if we can fine-tune command of the genetic code, it could correct around 89% of the mutations that cause genetic diseases in humans.

In lab scenarios, they’ve used these prime editors to fix the glitches that cause sickle cell anemia, cystic fibrosis, and Tay-Sachs disease, to name a few.

Gaetan Burgio, a geneticist not involved in the work, says,

“[It] has a strong potential to change the way we edit cells and be transformative.

Overall, the editing efficiency and the versatility shown in this paper are remarkable.”

The prime editors are huge, which might make them less practical, but they are much more accurate than their predecessors.

Said Liu,

“We believe this arises from the fact that prime editing requires three different pairing steps.

If any of those three events fail then prime editing can’t proceed.”

Liu and Anzalone aren’t letting that stop them, though. They’ve co-founded another company to work on tweaking the technology, and even though human experiments are likely years away, there is a light at the end of the tunnel – a tunnel that’s so much shorter than anyone could have believed even a decade ago.

Anzalone summed it up like this,