An analysis of disease severity based on SMN2 copy number in adults with spinal muscular atrophy

Muscle Nerve. 2009 Oct;40(4):652-6. doi: 10.1002/mus.21350.


To evaluate the effect of SMN2 copy number on disease severity in spinal muscular atrophy (SMA), we stratified 45 adult SMA patients based on SMN2 copy number (3 vs. 4 copies). Patients with 3 copies had an earlier age of onset and lower spinal muscular atrophy functional rating scale (SMAFRS) scores and were more likely to be non-ambulatory. There was, however, no difference between the groups in quantitative muscle strength or pulmonary function testing. Functional scale may be a more discriminating outcome measure for SMA clinical trials.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Activities of Daily Living
  • Adult
  • Amines / therapeutic use
  • Cohort Studies
  • Cyclohexanecarboxylic Acids / therapeutic use
  • Disability Evaluation
  • Excitatory Amino Acid Antagonists / therapeutic use
  • Female
  • Gabapentin
  • Gene Dosage*
  • Humans
  • Male
  • Middle Aged
  • Muscle Strength / physiology
  • Muscular Atrophy, Spinal / drug therapy
  • Muscular Atrophy, Spinal / genetics*
  • Muscular Atrophy, Spinal / pathology*
  • Phenotype
  • Respiratory Function Tests
  • Survival of Motor Neuron 2 Protein / genetics
  • gamma-Aminobutyric Acid / therapeutic use


  • Amines
  • Cyclohexanecarboxylic Acids
  • Excitatory Amino Acid Antagonists
  • SMN2 protein, human
  • Survival of Motor Neuron 2 Protein
  • gamma-Aminobutyric Acid
  • Gabapentin