WRAP53 and proximal spinal muscular atrophy: Other proteins enriched in the CB are the survival of motor neuron (SMN) protein, which is mutated in most cases of spinal muscular atrophy (Coady and Lorson, 2011), and WRAP53 (also known as TCAB1 or WDR79), which plays a pivotal role in RNP biogenesis (Tycowski et al., 2009; Venteicher et al., 2009; Mahmoudi et al., 2010; Stern et al., 2012).