One potential explanation suggested to clarify the aforementioned connection is the accumulation of adipose tissue within muscle mass, which may notably influence the regulation of ApN expression [27]; a decrease in ApN receptor signaling or increase in muscle catabolism may also occur due to the coexistence of other clinical entities, with all three pathophysiological entities being applicable in patients with SMA type 3. This evidence concerns the gene ANPEP and Proximal spinal muscular atrophy type 3.