Spinal muscular atrophy with lower extremity predominance (SMA-LED) is an extremely rare neuromuscular disorder of infants characterised by severe progressive muscle atrophy which is especially prominent in legs. The disorder is associated with a genetic mutation in the DYNC1H1 gene (the gene responsible also for one of the axonal types of Charcot–Marie–Tooth disease) and is inherited in an autosomal dominant manner. As with many genetic disorders, there is no known cure to SMA-LED.