Researchers reported a compact CRISPR-based gene-editing system designed for targeted delivery inside the body, aiming to address a key bottleneck for therapeutic genome editing. The approach uses a naturally occurring enzyme, Al3Cas12f, selected for its small size to fit into adeno-associated virus (AAV) vectors, followed by engineering that improved editing performance in human cells. The work focuses on efficiency and delivery feasibility in human cell contexts—critical constraints for in vivo editing programs, especially when vector capacity limits can restrict the use of larger Cas enzymes. While still preclinical, the reported up-to-90% efficiencies—along with the AAV compatibility goal—sets a clear benchmark for next-generation in-body editing constructs.