AQP4 and Hashimoto thyroiditis: Autoimmune diseases were also frequent in AQP4‐NMOSD, including systemic lupus erythematosus (SLE) (n = 17), Sjögren's syndrome (n = 11), myasthenia gravis (n = 9), and autoimmune thyroiditis (Hashimoto's disease) (n = 5) (Table S1).