DDX20 and proximal spinal muscular atrophy: Although we did not analyze the levels of Gemin3, Gemin5 and Gemin7 for lack of suitable antibodies, decreasing SMN expression in HeLa cells by RNA interference to an extent similar to that in the spinal cord of SMA mice significantly reduces the levels of Gemin2, Gemin6, Gemin7 and Gemin8 but not of Gemin3, Gemin4, Gemin5 or unrip proteins (Figure S1).