A long-term comparative analysis reported outcomes of AAV9-mediated gene replacement therapies in murine models of spinal muscular atrophy, according to the study summary provided. The work focuses on durability over time—one of the central questions for AAV-based SMA treatments. By comparing different engineered gene therapy approaches in animals over extended follow-up, the study aims to clarify which design choices hold up with longevity. The findings support ongoing optimization of dosing and vector strategy ahead of translation decisions.