UBA1 and proximal spinal muscular atrophy: In addition to displaying the obvious requirements of such a model (including reduced SMN protein and displaying the desired characterizations of diseased motor neurons Ebert and Svendsen, 2010; Sareen et al., 2012), we have been able to further validate the model via the identification, at the gene and protein level, of downstream consequences of reduced SMN that have been identified in other SMA model systems (e.g., UBA1, Wishart et al., 2014).