MUSK and myasthenia gravis: There are other autoimmune diseases associated with IgG4 antibodies, and some of these are neurological, including anti-muscle specific tyrosine kinease (MUSK) myasthenia gravis, leucine-rich glioma-inactivated (LGI)-1 and CASPR2 autoimmune syndromes, and anti-immunoglobulin LSAMP, OBCAM, Neurotrimin 5 (IgLON5) disorder disorder (298).