SMN1 and proximal spinal muscular atrophy: Chen et al. demonstrated that, among a list of miRNAs that function in the spinal cord and are enriched during motor neuron and/or interneuron development, miR-34a exhibits the most consistent downregulation during SMA onset and progression both in iPSC-derived motor neurons of type 1 SMA patients and in the spinal cord of SMNΔ7 mice [88].