Prime Editing and the Reprogrammable Human Genome
Science Time · 2019
"CRISPR 2.0 (Prime Editing) elevates genetic modification from a crude cutting tool to a precise word processor, unlocking the capability to cure most genetic diseases and propelling humanity into an era of directed, non-Darwinian evolution."
Mutations in DNA's 3 billion base pairs cause over 7,000 known genetic diseases. The original CRISPR-Cas9 let scientists cut DNA at specific locations to disable or insert genes, but Cas9 acts like scissors relying on the cell's own messy repair mechanisms — often introducing unpredictable off-target mutations. "Prime Editing" (CRISPR 2.0) acts less like scissors and more like a precise search-and-replace word processor for the genome.
Prime Editing uses a modified Cas9 that only nicks one strand of the double helix instead of breaking both, drastically reducing cellular trauma and the risk of catastrophic errors. It pairs the nicking enzyme with a pegRNA that locates the exact target sequence and carries the corrected genetic information; an attached reverse transcriptase writes the new code directly into the nicked strand. That gives it the accuracy to theoretically correct the large majority of known disease-causing genetic variants without unintended double-strand breaks.
How does Prime Editing fundamentally improve upon the original CRISPR-Cas9 system?
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The explanation above is written with AI assistance. These are the originals — go to them to check it.
- Prime Editing — search-and-replace genome editing (Anzalone et al., 2019)David Liu lab / Wikipedia
AlphaFold and the End of the Protein Folding Problem
"For fifty years, going from a protein's amino-acid sequence to its three-dimensional shape took months or years of experiment per protein. In 2020 a neural network did it in minutes at near-experimental accuracy, and two years later the predicted structure of nearly every catalogued protein was free to download."