SMN2 and proximal spinal muscular atrophy: As shown in Fig 5A, the scores of HFMS was significantly different depending on the SMN2 copy number (p < 0.01, two copies versus three and four copies), and the clinical subtypes of SMA (p < 0.001); type I versus type II (p < 0.05), type II versus type III (p < 0.05), and type I versus type III (p < 0.001).