Approximately 20% of patients with GFAP-A also have autoimmune diseases such as type 1 diabetes, autoimmune thyroid disease, and rheumatoid arthritis.[4] Some patients may have a combination of other positive antibodies, most commonly NMDA, AQP4, and MOG, and we have reported patients who did not show positive results for these antibodies. Here, AQP4 is linked to autoimmune thyroid disease.