AQP4 and neuromyelitis optica: Although the criteria1 set out to make DN NMO/NMOSD patients similar to AQP4-IgG+ patients, DN NMO/NMOSD patients have more frequent occurrence of simultaneous ON and LETM (likely because they are required to have two anatomical locations involved) but less than those with MOG-IgG.12,14,18 When compared with MOGAD, they are more likely to have LETM, more likely in the cervical spine, and less likely to have bilateral simultaneous ON or brain lesions.8,9,12,13, –15,17,18,22