A combined brain and optic nerve MRI study from Australia in 11 AQP4 ab–positive, 19 MOGAD, and 13 MS patients with a first ON in the investigated eye found more frequent optic nerve swelling in MOGAD and more frequent bilateral optic tract and chiasmal involvement in AQP4 ab–positive NMOSD (205). This evidence concerns the gene AQP4 and myeloid sarcoma.