SMN2 and proximal spinal muscular atrophy: Here, to achieve our goal, we study children with spinal muscular atrophy (SMA) typesII or IIIa, an autosomal recessive genetic disorder characterized by progressivedegeneration of primarily α-motoneurons due to mutations in the survival motorneuron 1 gene (SMN1), which encodes the survival motorneuron (SMN), a protein critical for the motoneurons’ survival (47).