SQSTM1 and proximal spinal muscular atrophy: LC3-II levels decrease in SMA patient muscle and fibroblasts but increase in motor neurons, suggesting tissue specific outcomes of SMN reduction. p62 decreases in SMA mice muscle suggesting an increase in autophagic flux. Conversely, p62 increases in SMA patient fibroblasts, suggesting a reduced autophagic flux. Similarly, p62 is increased in motor neurons, indicative of a reduced flux. mTOR signaling is found to be increased in motor neurons (autophagy inhibited); decreased in skeletal muscle and fibroblasts (autophagy activated).