The lack of oligodendrocyte differences in morphology, maturation, and myelination, between a severe SMA mice model (Smn−/−; SMN2) and WT mice was confirmed in in vivo studies by the same group as equivalent numbers of mature oligodendrocytes were found in corpus callosum, accompanied with normal myelination in the spinal cord [27]. Here, SMN2 is linked to proximal spinal muscular atrophy.