Spinal muscular atrophy with lower extremity predominance 1 (SMALED1) is an extremely rare neuromuscular disorder of infants characterised by severe progressive muscle
atrophy
Atrophy is the partial or complete wasting away of a part of the body. Causes of atrophy include mutations (which can destroy the gene to build up the organ), poor nourishment, poor circulation, loss of hormonal support, loss of nerve supply t ...
which is especially prominent in legs.
The disorder is associated with a genetic
mutation
In biology, a mutation is an alteration in the nucleic acid sequence of the genome of an organism, virus, or extrachromosomal DNA. Viral genomes contain either DNA or RNA. Mutations result from errors during DNA or viral replication, mi ...
in the ''
DYNC1H1''
gene
In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a ba ...
(the gene responsible also for one of the axonal types of
Charcot–Marie–Tooth disease) and is
inherited in an
autosomal dominant
In genetics, dominance is the phenomenon of one variant (allele) of a gene on a chromosome masking or overriding the effect of a different variant of the same gene on the other copy of the chromosome. The first variant is termed dominant and t ...
manner. As with many
genetic disorder
A genetic disorder is a health problem caused by one or more abnormalities in the genome. It can be caused by a mutation in a single gene (monogenic) or multiple genes (polygenic) or by a chromosomal abnormality. Although polygenic disorders ...
s, there is no known cure to SMALED1.
The condition was first described in a multi-generational family by Walter Timme in 1917. 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.
See also
*
Spinal muscular atrophies
*
Spinal muscular atrophy with lower extremity predominance 2A
*
Spinal muscular atrophy with lower extremity predominance 2B
References
Autosomal dominant disorders
Neurogenetic disorders
Neuromuscular disorders
Rare diseases
Systemic atrophies primarily affecting the central nervous system
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