title: Anti-MuSK antibody myasthenia gravis: clinical findings and response to treatment in two large cohorts.
abstract: BACKGROUND
  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.
authors.affiliation: Department of Medicine, Duke University Medical Center, Durham, North Carolina, USA.
authors.forename: Jeffrey T
authors.initials: JT
authors.lastname: Guptill
authors.forename: Donald B
authors.initials: DB
authors.lastname: Sanders
authors.forename: Amelia
authors.initials: A
authors.lastname: Evoli
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001323:Autoantibodies / Q000097:blood*; D002648:Child; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009157:Myasthenia Gravis / Q000097:blood / Q000276:immunology* / Q000628:therapy*; D010951:Plasma Exchange / Q000379:methods; D020794:Receptor Protein-Tyrosine Kinases / Q000097:blood / Q000276:immunology*; D011950:Receptors, Cholinergic / Q000097:blood / Q000276:immunology*; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D001323:Autoantibodies; D011950:Receptors, Cholinergic; C095714:MUSK protein, human; D020794:Receptor Protein-Tyrosine Kinases