Frequency of seronegativity in adult-acquired generalized myasthenia gravis

Ho Chan Koon, Daniel H. Lachance, C. Michel Harper, Vanda A. Lennon

Research output: Contribution to journalArticlepeer-review

67 Scopus citations


We determined the prevalence of muscle acetylcholine receptor (AChR) antibodies in patients with adult-acquired generalized myasthenia gravis (MG), the seroconversion rate at 12 months, and the prevalence of muscle-specific tyrosine kinase (MuSK) antibody among persistently seronegative patients. We identified 562 consecutive Mayo Clinic patients with MG based on clinical and electrophysiological criteria. At presentation, 508 patients (90.4%) tested positive for AChR binding or AChR modulating antibodies. After 12 months, 15.2% of initially seronegative patients had become seropositive, yielding a seronegativity rate of 8.2% (95% confidence interval: 6.2-9.6%). Among seronegative patients not receiving immunosuppressants, 38% were MuSK antibody-positive and 43% were seropositive for nonmuscle autoantibodies. Classification as seronegative MG should be reserved for nonimmunosuppressed patients with generalized MG who lack muscle AChR binding, AChR modulating, or MuSK antibodies at presentation and at follow-up of at least 12 months.

Original languageEnglish (US)
Pages (from-to)651-658
Number of pages8
JournalMuscle and Nerve
Issue number5
StatePublished - Nov 2007


  • AChR antibody
  • Adult-acquired myasthenia gravis
  • Autoantibody evaluation
  • MuSK antibody
  • Seronegative myasthenia gravis

ASJC Scopus subject areas

  • Physiology
  • Clinical Neurology
  • Cellular and Molecular Neuroscience
  • Physiology (medical)


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