Serum MOG-IgG and AQP4-IgG antibody titer levels in CNS demyelinating diseases and controls. Serum AQP4-IgG (upper panel) were exclusively detected in serum samples of patients with NMO and HR-NMO and one CIS patient, but not in any subjects with ADEM, MS and CTRL. Serum MOG-IgG (lower panel) were present at highest titers (≥ 1:160, indicated by a dotted vertical line) in a cohort of patients with ADEM, AQP4-IgG seronegative HR-NMO (pink squares) and in both AQP4-IgG seronegative NMO subjects (blue squares, both at a MOG-IgG titer of 1:2,560) as well as in two CIS samples (green triangles). One patient (NMO) was found to be double positive for MOG-IgG (blue square at the threshold level of 1:160, lower panel) and AQP4-IgG (blue square at a titer of 1:1,280; upper panel). Coloured icons indicate individual patients in the upper and lower panel.