It is presumed to be an antibody-mediated disorder, the target antigen being the water channel aquaporin-4 (AQP4) on astrocyte cell membranes.[1, 2] We recently reviewed the major advances in NMO over the last decade in this Journal.[3] This update summarizes the developments in the last 2 years. Here, AQP4 is linked to neuromyelitis optica.