Al3Cas12f RKK Hits 90% Gene Editing Efficiency
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- Researchers at the University of Texas at Austin identified Al3Cas12f, a naturally occurring CRISPR enzyme small enough to fit inside adeno-associated virus (AAV) vectors, the leading targeted-delivery vehicle for gene therapies.
- Al3Cas12f forms a more stable, tightly connected complex than other comparably small enzymes, allowing it to function more effectively in human cells shortly after assembly, according to structural analysis using imaging and machine learning.
- The engineered variant Al3Cas12f RKK boosted editing efficiency from less than 10% to more than 80% across tested targets, reaching 90% in a commonly edited region of the genome.
- Tests were conducted in human cells originally isolated from a leukemia patient, targeting genes linked to cancer, atherosclerosis, and amyotrophic lateral sclerosis (ALS).
- The advance addresses a core limitation of current CRISPR systems: widely used editors like Cas9 are too large for AAV packaging, restricting clinical use to ex vivo editing of cells such as blood and bone marrow.
- Erica Brown, acting director of NIH's NIGMS, called the finding a significant step toward smart, in-body delivery of gene-editing systems with broad clinical implications.
- The study, published in Nature Structural & Molecular Biology, is funded by NIH; the team's next step is testing the nuclease's performance once packaged into AAV vectors.
Why it matters: Standard CRISPR editors are too large for AAV vectors, the leading in-body delivery vehicle, so gene therapies today are mostly limited to cells removed, edited, and reinfused. Al3Cas12f RKK combines AAV-compatible size with 90% editing efficiency, potentially opening in-vivo treatment of diseases like cancer, atherosclerosis, and ALS that current delivery constraints make unreachable.
