Spinal muscular atrophy with lower extremity predominance 1 (SMALED1) is an extremely rare neuromuscular disorder of infants characterised by severe progressive muscle atrophy which is especially prominent in legs.

[1] 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)[2][3] and is inherited in an autosomal dominant manner.

As with many genetic disorders, there is no known cure to SMALED1.

[citation needed] The condition was first described in a multi-generational family by Walter Timme in 1917.

[4] Its linkage to the DYNC1H1 gene was discovered in 2010 by M. B. Harms, et al., who also proposed the current name of the disorder.