Anti muscle specific kinase antibody syndrome
What is anti muscle specific kinase antibody syndrome (anti MuSK antibody syndrome)?
A new population of antibodies has been identified in Myasthenia gravis patients in recent years, directed against MuSK.
MuSK is a tyrosine kinase, which has an important role in regulating and maintaining AChRs and their functional clusters at the Neuromuscular Junction.
Anti-MuSK antibodies may be found in 40% to 60% of patients with clinical Myasthenia gravis who are seronegative for antibodies directed against the AChR, and passive transfer of these antibodies produces physiologic effects at the Neuromuscular Junction similar to that caused by anti-AChR IgG (i.e., reduced MEPP amplitude).
Initial clinical studies suggest that these patients have a syndrome of generalized myasthenia, often with prominent neck, shoulder, or respiratory muscle weakness with little or delayed ocular muscle involvement.
Responses to cholinesterase inhibitors are variable, but PE is effective, and most patients also respond to other immunotherapies including oral steroids, azathioprine, cyclosporine, and mycophenolate.
The benefits of thymectomy remain unclear at present.
