AQP4 and myeloid sarcoma: They include multiple sclerosis (MS), for which the autoimmune targets of CNS-infiltrating T and B lymphocytes are not yet fully understood (1), myelin oligodendrocyte glycoprotein (MOG) antibody associated disorders (MOGAD) which were previously considered to be part of the MS spectrum and in which the oligodendrocyte protein MOG is a major candidate autoantigen (2, 3), and neuromyelitis optica spectrum disorders (NMOSD) with an autoimmune response that targets aquaporin-4 on astrocytes.