Rallapalli, K. L.; Ho, J.; Nocedal, I.; Tan, J. W.; Ocampo, R. F.; Thomas, N. C.; Justice, B.; Jirde, S.; Gonzalez-Osorio, L.; Castelle, C. J.; Lin, J.-L.; Wright, J. T.; Toch, S.; Shah, K.; Freeman, B.; Rehman, J.; Muysson, J.; Krudop, I.; Alexander, L. M.; Brooks, A. R.; Brown, C. T.; Goltsman, D. S. A.; Hoff, K. G.; Szymanski, P.; Thomas, B. C.; Taylor, D. W.; Butterfield, C. N.

Adenine base editors (ABEs) have emerged as a powerful gene-editing technology enabling precise and programmable adenine-to-guanine substitutions across the genome. However, their translation into in vivo therapeutics is limited by delivery challenges, as their size exceeds the packaging capacity of adeno-associated virus (AAV). Here, we report the discovery, structural characterization, and engineering of two compact, highly active ABEs built on novel deaminases and Cas9d nucleases, enabling all-in-one, single-vector AAV delivery. Applying these compact ABEs to Duchenne muscular dystrophy (DMD), we demonstrate efficient disruption of conserved splice-acceptor sites at dystrophin exons 45 and 51 in human skeletal muscle cells, enabling therapeutically relevant exon skipping. Together, these ABEs help expand the therapeutic reach of base editing towards diverse tissue types and disease targets.