SMN1 and proximal spinal muscular atrophy: Attenuation of SMA pathology has been observed in a zebrafish model of SMA by over-expression of candidate plasticity-related gene 15 (cpg15), an mRNA known to be present in axons, which is found in complex with the neuronal RNA binding protein (RBP) HuD and SMN, suggesting that SMN-containing complexes are involved in translocation of mRNA species required for the health and maintenance of motor neurons [16].