In this trial, NMO-SD patients with current or previous AQP4 seropositivity, and an Expanded Disability Status Scale (EDSS) score of 7.0 or less, were randomly assigned (1:1) treatment with rituximab (intravenous [IV], every week for 4-weeks and then 6-month interval dosing; n = 19) or placebo (matched administration; n = 19). This evidence concerns the gene AQP4 and neuromyelitis optica.