In the AQP4-NMOSD cohort, the most common AIDs observed were autoimmune thyroiditis (n = 18), followed by systemic lupus erythematosus (n = 8), myasthenia gravis (n = 7), and rheumatoid arthritis (n = 7), and Sjögren’s syndrome (n = 5). Here, AQP4 is linked to rheumatoid arthritis.