Anti-MuSK antibody myasthenia gravis: clinical findings and response to treatment in two large cohorts

Muscle Nerve. 2011 Jul;44(1):36-40. doi: 10.1002/mus.22006.


Introduction: Myasthenia gravis (MG) patients with autoantibodies to muscle-specific tyrosine kinase (MuSK) represent a distinct subset of those with this disease. Treatment and outcomes data in these patients are limited and conflicting.

Methods: We reviewed 110 MuSK-MG patients from two large clinics in Italy and the USA.

Results: Thirty-nine to 49% of patients with generalized, acetylcholine receptor antibody (AChR-Ab)-negative MG had MuSK-MG. Eighty-five percent were female, with disease onset typically in the fourth decade. Ocular and/or bulbar symptoms were present at onset in 79% of those studied. Eighty-five percent were MGFA class III or greater, and crisis occurred in 28%. Plasma exchange (PLEX) produced improvement in 93%, whereas only 61% improved after intravenous immunoglobulin. Long-term outcomes were comparable to those of patients with AChR-Ab-positive MG.

Conclusions: MuSK-MG has a marked female predominance with frequent oculobulbar weakness and crises. Many patients deteriorate rapidly early in the disease, and PLEX is usually the preferred treatment. Long-term outcomes are similar to those of patients with AChR-Ab(+) MG.

Publication types

  • Comparative Study
  • Multicenter Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Autoantibodies / blood*
  • Child
  • Cohort Studies
  • Female
  • Follow-Up Studies
  • Humans
  • Male
  • Middle Aged
  • Myasthenia Gravis / blood
  • Myasthenia Gravis / immunology*
  • Myasthenia Gravis / therapy*
  • Plasma Exchange / methods
  • Receptor Protein-Tyrosine Kinases / blood
  • Receptor Protein-Tyrosine Kinases / immunology*
  • Receptors, Cholinergic / blood
  • Receptors, Cholinergic / immunology*
  • Treatment Outcome
  • Young Adult


  • Autoantibodies
  • Receptors, Cholinergic
  • MUSK protein, human
  • Receptor Protein-Tyrosine Kinases