The onset age of most of our type I SMA patients (38/41, 92.7 %) was <2 months and 72.4 % (21/29) of type II SMA patients carried more than 3 copies of SMN2, whereas the onset age of Qu’s type I patients was 31.1 % (33/106) and copies of SMN2 of Qu’s type II patients was 96 %. This evidence concerns the gene SMN2 and proximal spinal muscular atrophy.