Co-existing autoimmune diseases are observed in up to 7–10% of MOGAD patients, with Sjogren syndrome, rheumatoid arthritis, ulcerative colitis, thyroid disorder, psoriasis, and NMDAR encephalitis being commonly reported (16, 31, 34, 35, 39), but the frequency appears to be lower than that in AQP4+ NMOSD (40). Here, AQP4 is linked to autoimmune disease.