However, the bouquet of clinical phenotypes in MOG-IgG-associated diseases at clinical onset is not easy to differentiate and overlaps with aquaporin-4-IgG (AQP4-IgG)-seropositive NMOSD and in rare cases with MS [2, 10–12], although distinct clinical features such as seizures have been described [13–15]. The gene discussed is AQP4; the disease is myeloid sarcoma.