However, when a conformationally correct and glycosylated human MOG was used to identify MOG autoantibodies in serum and CSF, they were not found in patients with MS but were rather found in about 40% of patients diagnosed with ADEM or aquaporin 4 IgG–negative (AQP4-IgG–) neuromyelitis optica spectrum disorder (NMOSD) (3–7). The gene discussed is AQP4; the disease is myeloid sarcoma.