Anti-MuSK- and anti-AChR-positive myasthenia gravis induced by d-penicillamine.
BACKGROUND
Myasthenia gravis (MG) is an autoimmune disorder of the neuromuscular junction usually caused by antibodies to the nicotinic acetylcholine receptor (AChR) and occasionally to muscle-specific kinase (MuSK). D-penicillamine is a therapeutic agent for several diseases, but can also induce a number of immune-mediated disorders, including MG, as a side-effect. In most patients with D-penicillamine-induced MG, anti-AChR antibodies are detected, but the presence of anti-MuSK antibodies has not been reported previously.


METHODS
The case reported was a female patient who presented with myasthenic symptoms after D-penicillamine administration for scleroderma.


RESULTS
Both anti-AChR and anti-MuSK antibodies were identified in the patient's serum. The anti-MuSK antibodies were of the IgG4 subclass, as in idiopathic MG. Both types of antibody gradually disappeared after discontinuation of D-penicillamine. A significant improvement in symptoms was observed and the patient gradually became free of MG symptoms, without requiring any treatment for MG. Another four double-positive (anti-AChR and anti-MuSK antibodies) patients were identified during a retrospective study, but none had been treated with D-penicillamine.


CONCLUSIONS
D-penicillamine can cause anti-AChR and anti-MuSK antibody-positive MG, a rare phenomenon which is reversed after discontinuation of D-penicillamine treatment.
Department of Pharmacy, University of Patras, GR 26500, Patras, Greece. kpoulas@upatras.gr
Konstantinos
K
Poulas
Euphrosyni
E
Koutsouraki
Gregory
G
Kordas
Anna
A
Kokla
Socrates J
SJ
Tzartos
D000368:Aged; D018501:Antirheumatic Agents / Q000009:adverse effects*; D001323:Autoantibodies / Q000097:blood / Q000276:immunology; D001324:Autoantigens / Q000276:immunology; D005260:Female; D006801:Humans; D009157:Myasthenia Gravis / Q000139:chemically induced* / Q000276:immunology; D010396:Penicillamine / Q000009:adverse effects*; D020794:Receptor Protein-Tyrosine Kinases / Q000276:immunology*; D011950:Receptors, Cholinergic / Q000276:immunology*; D012595:Scleroderma, Systemic / Q000188:drug therapy / Q000503:physiopathology
D018501:Antirheumatic Agents; D001323:Autoantibodies; D001324:Autoantigens; D011950:Receptors, Cholinergic; C095714:MUSK protein, human; D020794:Receptor Protein-Tyrosine Kinases; D010396:Penicillamine