Prior studies from our groups have shown that cumulative axonal damage, macular GCIPL thinning, and visual loss are typically more severe in AQP4-IgG+ON than in MS-ON and MOG-IgG+ON (89–91), and higher grade pRNFL swelling is closely correlated with MOG-IgG+ON in distinction to MS-ON (30). The gene discussed is AQP4; the disease is myeloid sarcoma.