For example, the Smn-/-;SMN2;SMNΔ7 mouse model of SMA (herein referred to as the delta 7 mouse model) contains 2 copies of the human SMN2 onto a Smn-/- background and also carries 2 copies of the delta 7 SMN cDNA. This evidence concerns the gene SMN1 and proximal spinal muscular atrophy.