SMN1 and proximal spinal muscular atrophy: This clinical data augments findings from preclinical and histopathological studies, which have underlined the specific function of SMN in axogenesis, axonal sprouting, neuronal migration and differentiation in the central nervous system.27,28 Further, post-mortem histopathological data from untreated children with SMA have shown the effects of SMN depletion on brain structures, including the thalami, basal ganglia, temporal and frontal cortices, hippocampi and cerebellum, with progression in changes over time.1,29