About 80% of patients with type I SMA have one or two SMN2 copies, 82% of type II SMA patients have two or three SMN2 copies, 96% of patients with type III SMA have three or four SMN2 copies and 75% of type IV SMA patients harbor four SMN2 copies [4, 5]. This evidence concerns the gene SMN2 and proximal spinal muscular atrophy.