While preliminary evidence from a number of case studies (AQP4-Ab-positive and -negative; systemic lupus erythematosus- and Sjögren’s syndrome-associated; daily oral dose in one, IV pulse in six, immunoablative in one; combination with steroids, IVIg, or AZA in all) suggested a possible treatment response to cyclophosphamide (CYC) [100, 198–201], a recent retrospective analysis of seven Brazilian NMO cases (pulsed IV CYC) failed to show such effect [202]. The gene discussed is AQP4; the disease is neuromyelitis optica.