The mechanisms underlying initiation and evolution of spinal cord lesions in NMOSD also recapitulate important aspects of the formation of brain lesions in MS [51▪▪]: In AQP4-abpositive NMOSD, initial lesions preferentially form in the posterior and lateral columns which have a poor circulatory reserve, whereas in MS brains, plaques preferentially develop in hypo-perfused CNS white matter [51▪▪,54–57]. The gene discussed is AQP4; the disease is myeloid sarcoma.