(SMN1) Spinal Muscular Atrophy Type I
• Cell line states: affected
• Defects in SMN1 cause spinal muscular atrophy, a group of autosomal
recessive neuromuscular disorders characterized by degeneration of the anterior
horn cells of the spinal cord, leading to symmetrical muscle weakness and atrophy.
SMA is the second most common lethal, autosomal recessive disease in Caucasians
after cystic fibrosis. Four types of SMA are recognized depending on the age
of onset, the maximum muscular activity achieved, and survivorship: type I,
severe infantile acute SMA, or Werdnig-Hoffman disease; type II, or infantile
chronic SMA; type III, juvenile SMA, or Wohlfart-Kugelberg-Welander disease;
and type IV, or adult-onset SMA. All types are caused by recessive mutations
in the SMN1 gene.