Spinal muscular atrophy: Selective motor neuron loss and global defect in the assembly of ribonucleoproteins.

•SMA is caused by defects in ribonucleoprotein (RNP) complex formation.•The SMN protein is a platform for the association of RNA and RNA binding proteins.•SMN has essential roles in global and neuron-specific RNA processing pathways.•Selective vulnerability of motor neurons may be due to a confluence of RNP formation defects.