Different characteristic phenotypes according to antibody in myasthenia gravis

J Clin Neuromuscul Dis. 2012 Dec;14(2):57-65. doi: 10.1097/CND.0b013e318275197c.


Objectives: To find the characteristic phenotypes of 3 different types of myasthenia gravis (MG).

Methods: The clinical and electrophysiological features among 15 cases of muscle-specific kinase antibody positive (MuSK Ab+) MG, 59 cases of double seronegative (DSN) MG, and 161 cases of acetylcholine receptor antibody (AChR Ab)+ MG in the University of Alabama at Birmingham were compared.

Results: AChR Ab was positive in 69% of cases and MuSK Ab in 6% of cases. MuSK Ab+ MG was more common (14%) in African Americans compared with whites (4%). AChR Ab+ MG is characterized by male predominance, later onset, a fewer cases of ocular MG, and a higher association with thymoma. DSN-MG is characterized by a greater prevalence of ocular MG, milder forms of MG with less number of crisis, and fewer abnormalities in the repetitive nerve stimulation test. MuSK Ab+ MG is characterized by younger age at onset, severe and bulbar forms of MG, predominant faciobulbar neck weakness, and a poor response to edrophonium, anticholinesterase, and intravenous immunoglobulin. Long-term outcome showed no difference among 3 types of MG.

Conclusions: AChR Ab+ MG and DSN-MG are similar, with the exception of less severity in the latter. MuSK Ab+ MG has distinct clinical and electrophysiological features.

MeSH terms

  • Adolescent
  • Adult
  • Age of Onset
  • Aged
  • Autoantibodies / metabolism*
  • Chi-Square Distribution
  • Cholinesterase Inhibitors / therapeutic use
  • Electric Stimulation
  • Electromyography
  • Evoked Potentials, Motor / physiology
  • Female
  • Humans
  • Immunoglobulins, Intravenous / therapeutic use
  • Immunologic Factors / therapeutic use
  • Longitudinal Studies
  • Male
  • Middle Aged
  • Myasthenia Gravis / classification*
  • Myasthenia Gravis / immunology*
  • Myasthenia Gravis / therapy
  • Neural Conduction / physiology
  • Phenotype*
  • Pyridostigmine Bromide / therapeutic use
  • Receptor Protein-Tyrosine Kinases / immunology
  • Receptors, Cholinergic / immunology
  • Retrospective Studies
  • Young Adult


  • Autoantibodies
  • Cholinesterase Inhibitors
  • Immunoglobulins, Intravenous
  • Immunologic Factors
  • Receptors, Cholinergic
  • MUSK protein, human
  • Receptor Protein-Tyrosine Kinases
  • Pyridostigmine Bromide