After years of conflicting research on the role of MOG-IgG antibodies in neuroinflammatory diseases, the methodological improvements using more reliable cell-based assays presenting human MOG protein in a biosimilar conformation have identified typical clinical presentations associated with anti-MOG-IgG antibodies, now called MOG-IgG-associated encephalomyelitis (MOG-EM). The gene discussed is MOG; the disease is encephalomyelitis.