RUNX1 and proximal spinal muscular atrophy: AAV vectors are widely used for cardiac gene delivery in pre-clinical models and clinical trials29 and a licensed AAV9 gene therapy is available for the treatment of spinal muscular atrophy.30 AAV9 encoding shRNA provides highly efficient knockdown in the heart.31 RNAscope was performed to confirm the ability of the shRNA to knock-down Runx1 in BZ cardiomyocytes and are detailed in the methods (see Supplementary material online, Figure S8B and D), AAV9-Runx1-shRNA or control AAV-scramble-shRNA were delivered via tail-vein injection following MI in C57BL/6J mice (Figure 4D).