SMN2 and proximal spinal muscular atrophy: For example, cardiac defects have been reported in a range of animal models of SMA, the severity of which may not be directly related to SMN levels.12,13,14 We have therefore focused our attention on the potential for PTEN knockdown to ameliorate disease pathology in SMA, since we first reported that experimental targeting of PTEN increases neuronal survival following ischemic injury in vitro and in vivo.