We demonstrated that the levels of a subset of Gemin proteins (namely Gemin2, Gemin6 and Gemin8) are significantly reduced in the spinal cord of severe SMA mice compared with normal mice, and that Gemin8 is an integral component of the SMN complex whose expression is most severely affected by decreased SMN (Figures 1 and S1). Here, SMN2 is linked to proximal spinal muscular atrophy.