AQP4 and autoimmune disease: The sex difference between MOGAD patients in this study was not statistically significant, and the male-to-female ratio was 1.16:1, which is consistent with previous studies, and these studies have shown a male-to-female ratio of approximately 1:1 (18), which differs from the female bias often observed in other immune-mediated/autoimmune diseases, including AQP4-IgG + NMOSD (1:9.2) and MS (1:3) (19–21).