Serum of patients were analyzed: 8 NMOSD, 94 MS, 39 optic neuritis (ON), 29 idiopathic myelitis, 9 other idiopathic demyelinating processes of CNS, 18 other neurological disorders and 8 controls, and the assay was performed over AQP1- or AQP4-transfected HEK293 cells, either permeabilized with triton X-100 or untreated. The gene discussed is AQP4; the disease is myeloid sarcoma.