Since a marked significant difference was observed between control and SMA subjects in the case of SMN spot analysis (Figs 3C and 4C, and online Supporting S4 Table), we next compared the percentages of SMN-spot+ cells and SMN spot MFI in CD33++ cells on the basis of the SMN2 copy number, the clinical subtypes of SMA, and the scores of HFMS. This evidence concerns the gene CD33 and proximal spinal muscular atrophy.