In contrast, the cohort described by Sun et al. (2020) seems to have, in global numbers, a better-than-expected phenotype, as the majority of SMA type II patients presented 2 SMN2 genes, type III patients had 2 or 3 SMN2 copies and more than half of SMA type IV had only 3 SMN2 genes [35]. The gene discussed is SMN2; the disease is spinal muscular atrophy, type IV.