NAIP and proximal spinal muscular atrophy: Recently, in addition to the NAIP gene [85,86], other factors have been reported, such as plastin 3 as a protective factor for axonal growth [87] and neurocalcin D, which restores endocytosis at the neuromuscular junction [88], which is why it is becoming increasingly important to evaluate other factors that allow for determining the prognosis of patients with SMA.