Optic neuritis (ON) is an inflammatory disorder of the optic nerve associated with immune-mediated chronic demyelinating diseases of the central nervous system (CNS), such as multiple sclerosis (MS), neuromyelitis optica spectrum disorder (NMOSD), and myelin oligodendrocyte glycoprotein (MOG) antibody-associated disorder1–5. This evidence concerns the gene MOG and myeloid sarcoma.