DYNC1H1 and proximal spinal muscular atrophy: Errors in the heavy chain of dynein, encoded by dynein cytoplasmic 1 heavy chain 1 (DYNC1H1) gene, have been implicated in spinal muscular atrophy with lower extremity predominance (SMA-LED), Charcot-Marie-Tooth disease type 2 (CMT2) and intellectual disability (reviewed in [8]; see also [9]).