SMN2 and proximal spinal muscular atrophy: This has been characterised in different mouse models of SMA, including the Smn-/-;SMN2 (life expectancy 6 days) [14, 24, 25], SMNΔ7/Δ7;SMN2 aka Taiwanese (life expectancy 8–10 days) [29] and Smn-/-;SMN2;SMNΔ7/Δ7 aka SMNΔ7 (life expectancy 13 days) [14, 20, 28].