SMN1 and proximal spinal muscular atrophy: These phenotypes are shared by other intermediate SMA models with point mutations (Smn2B/− mice) or exon deletions (SmnF7/Δ7, NSE-Cre mice) in murine Smn, although these strains lack an SMN2 transgene, which is being actively pursued as a therapeutic target in human SMA (Park et al, 2010a).