AQP4 and systemic lupus erythematosus: The presence of coexistent autoimmunity is more commonly observed in NMOSD compared with MS and MOGAD, and this particularly holds true for AQP4-IgG NMOSD which has a well-recognized overlap with systemic lupus erythematosus, Sjogren’s disease, autoimmune thyroid disorders, and myasthenia gravis (Table 1).35,36 Compared with around half of AQP4-IgG+ NMOSD, 4.6%–48% DN NMOSD patients were tested positive for antinuclear antibodies.8,13 Unmatched CSF oligoclonal bands (OCBs) were found in 8% to 23% of DN NMOSD,8,14 which is lower than MS.