Spinal muscular atrophy with lower extremity predominance 1 explained

Synonyms:	Lower extremity predominant spinal muscular atrophy type 1, SMALED1
Field:	Neurology
Symptoms:	Progressive muscle atrophy in legs
Onset:	Infancy
Causes:	Mutation in DYNC1H1 gene
Diagnosis:	Molecular test

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.

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)^{[1] [2]} and is inherited in an autosomal dominant manner. As with many genetic disorders, there is no known cure to SMALED1.

The condition was first described in a multi-generational family by Walter Timme in 1917.^[3] 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.^[4]

See also

• Spinal muscular atrophies
• Spinal muscular atrophy with lower extremity predominance 2A
• Spinal muscular atrophy with lower extremity predominance 2B

Notes and References

1. Harms MB, Ori-McKenney KM, Scoto M, Tuck EP, Bell S, Ma D, Masi S, Allred P, Al-Lozi M, Reilly MM, Miller LJ, Jani-Acsadi A, Pestronk A, Shy ME, Muntoni F, Vallee RB, Baloh RH . 2012 . Mutations in the tail domain of DYNC1H1 cause dominant spinal muscular atrophy . Neurology . 78 . 16 . 1714–20. 10.1212/WNL.0b013e3182556c05 . 22459677 . 3359582.
2. Tsurusaki . Y. . Saitoh . S. . Tomizawa . K. . Sudo . A. . Asahina . N. . Shiraishi . H. . Ito . J. I. . Tanaka . H. . Doi . H. . Saitsu . H. . Miyake . N. . Matsumoto . N. . A DYNC1H1 mutation causes a dominant spinal muscular atrophy with lower extremity predominance . 10.1007/s10048-012-0337-6 . Neurogenetics . 13 . 4 . 327–332 . 2012 . 22847149. 254112503 .
3. Timme . W. . Progressive Muscular Dystrophy As an Endocrine Disease . XIX. 10.1001/archinte.1917.00080200084004 . Archives of Internal Medicine . 79–104 . 1917 . 10192/31015 . free .
4. Harms . M. B. . Allred . P. . Gardner . R. . Fernandes Filho . J. A. . Florence . J. . Pestronk . A. . Al-Lozi . M. . Baloh . R. H. . 10.1212/WNL.0b013e3181ec800c . Dominant spinal muscular atrophy with lower extremity predominance: Linkage to 14q32 . Neurology . 75 . 6 . 539–546 . 2010 . 20697106. 2918478 .