SMN1 and proximal spinal muscular atrophy: Enriched within a CB are, in addition to other proteins and non-coding RNAs, the survival of motor neuron protein (SMN, encoded by SMN1 and SMN2), which is mutated in most cases of spinal muscular atrophy; WRAP53, which contributes to telomerase holoenzyme assembly; and coilin, which is canonically known as the CB marker protein (Liu and Dreyfuss, 1996; Mahmoudi et al., 2010; Matera and Frey, 1998; Young et al., 2000).