The aim of this study was to conduct a proteomic comparison of heart tissues from the less-severe Smn2B/− SMA mouse model and age-matched WT mice and compare these findings with those identified in our previous study of heart tissues from the severe Taiwanese SMA mouse model (15) to determine whether a conserved response to reduced SMN levels is evident. Here, SMN1 is linked to proximal spinal muscular atrophy.