MUSK and myasthenia gravis: Theoretically, as AChR antibodies are mainly IgG1 to IgG3 (produced by long-lived plasma cells that do not express CD20), while the main subtype of MuSK antibodies is IgG4, which is generated by short-lived plasmablasts, rituximab (RTX), a chimeric anti-CD20 monoclonal antigen, has no impact on long-lived plasma cells and demonstrates a better therapeutic effect on patients with MuSK-MG (14, 15).