The sex ratio in our cohort (1:2.8) did neither differ from that previously reported in AQP4-IgG-negative NMO patients with and without brainstem lesions (1:2; n = 27) [20] nor from that in the total MOG cohort (1:2.8; n = 50) [17] (but is in stark contrast to the sex ratio of ~1:9 reported in AQP4-IgG-positive patients [20]), indicating that female gender is probably not a risk factor for the development of brainstem involvement in patients with MOG-IgG-positive ON and/or myelitis. Here, AQP4 is linked to neuromyelitis optica.