Spinal muscular atrophy (SMA) is a rare autosomal recessive neurodegenerative disease affecting 1 in 10,000 to 11,000 births,1,2 approximately 400 infants in the United States each year.3 Spinal muscular atrophy is the most common fatal genetic disease of infancy.1,4 Unlike with other degenerative motor neuron diseases, the greatest loss of motor strength and function occurs at the onset of SMA; the disease then progresses slowly, until, in many cases, early death.5 Clinical presentation includes a wide range of phenotypes that are classified into groups based on age at disease onset, maximal motor function achieved, clinical course, and survival6,7 (see Table).
Spinal muscular atrophy type 1, also known as acute infantile SMA or Werdnig-Hoffman disease, is the most common and severe form seen in the acute care setting.10 Reports of impaired fetal movements are observed in 30% of...