SMN1 and proximal spinal muscular atrophy: In addition, we identified that the lower dose of 1 μM oxandrolone in vitro attenuated canonical atrophy in C2C12 myotubes, while in vivo oxandrolone attenuated neuromuscular dysfunction in severe SMA C. elegans model, suggesting that in both our SMA vertebrate and invertebrate species oxandrolone may be a beneficial SMN-independent treatment option.