Mouse Monoclonal Musk Antibody

The muscle-specific tyrosine kinase (MuSK) antibody is associated with a subtype of myasthenia gravis (MG), an autoimmune neuromuscular disorder. Discovered in 2001. MuSK antibodies are found in approximately 40% of patients with generalized MG who lack antibodies against the acetylcholine receptor (AChR), termed "seronegative MG." MuSK, a transmembrane protein critical for neuromuscular junction (NMJ) development, interacts with agrin and low-density lipoprotein receptor-related protein 4 (LRP4) to cluster AChRs during synaptogenesis. In autoimmune MG, MuSK antibodies (predominantly IgG4 subclass) disrupt this signaling, impairing AChR clustering and destabilizing NMJ integrity. Clinically, MuSK-MG often presents with prominent bulbar, facial, and respiratory weakness, distinguishing it from AChR-MG. Patients may show poor response to acetylcholinesterase inhibitors but better outcomes with immunosuppressants, rituximab, or plasma exchange. The exact trigger for autoimmunity remains unclear, though genetic factors (e.g., HLA-DQ5) and thymic abnormalities are less common than in AChR-MG. MuSK antibody detection via cell-based assays or radioimmunoprecipitation aids diagnosis, complementing clinical and electrophysiological findings. Research continues to explore pathophysiological mechanisms and targeted therapies for this distinct MG subtype.