NRXN2 and proximal spinal muscular atrophy: Abnormal splicing of particular genes such as Neurexin 2 (NRXN2), which coordinates synapse development, and Ubiquitin like modifier activating enzyme 1 (UBA1), whose function is to regulate ubiquitin levels, have been proposed to trigger neuromuscular specific phenotypes observed in SMA (See et al., 2014; Wishart et al., 2014).