AAV-mediated gene therapies by miniature gene editing tools

The advent of CRISPR-Cas has revolutionized precise gene editing. While pioneering CRISPR nucleases like Cas9 and Cas12 generate targeted DNA double-strand breaks (DSB) for knockout or homology-directed repair, next generation CRISPR technologies enable gene editing without DNA DSB. Base editors directly convert bases, prime editors make diverse alterations, and dead Cas-regulator fusions allow nuanced control of gene expression, avoiding potentially risks like translocations. Meanwhile, the discovery of diminutive Cas12 orthologs and Obligate Mobile Element-Guided Activity (OMEGA) nucleases has overcome cargo limitations of adeno-associated viral vectors, expanding prospects for in vivo therapeutic delivery. Here, we review the ever-evolving landscape of cutting-edge gene editing tools, focusing on miniature Cas12 orthologs and OMEGA effectors amenable to single AAV packaging. We also summarize CRISPR therapies delivered using AAV vectors, discuss challenges such as efficiency and specificity, and look to the future of this transformative field of in vivo gene editing enabled by AAV vectors delivery.