SMN2 and proximal spinal muscular atrophy: It should be noted that expression of these changes in terms of the ratio between full length SMN2 and SMNΔ7 transcripts as used by some authors is likely to exaggerate the magnitude of the potential beneficial effect, the significance of which is questionable especially given the observation that introduction of a SMNΔ7 transgene actually improves the phenotype of SMA mice [29].