Histone deacetylase (HDAC) inhibitors have been investigated in SMA models since the early discovery that histone acetylation controls SMN expression.67, 68, 69 Multiple HDAC inhibitors are either currently licensed or in clinical trials for cancer treatments (Table 2); hence, they make attractive therapies for alternative indications due to their known safety profiles. Here, HDAC9 is linked to proximal spinal muscular atrophy.