NCIt synonyms : Severe Infantile Spinal Muscular Atrophy; Spinal Muscular Atrophy, Type I; Spinal Muscular Atrophy Type 1;
NCIt related terms : Infantile spinal muscular atrophy, type I [Werdnig-Hoffman];
NCIt definition : The most severe form of spinal muscular atrophy. It is manifested in the first year
of life with muscle weakness, poor muscle tone, and lack of motor development. The
motor neuron death affects the major organ systems, particularly the respiratory system.
Most patients die before the age of two secondary to pneumonia.;