For CNS autoimmune syndromes, well-validated disease-specific fluid biomarkers already guide diagnosis and management: serum and CSF anti-AQP4 and anti-MOG autoantibodies are clinically established for discriminating neuromyelitis optica spectrum disorder (NMOSD), MOG-antibody disease and MS-like presentations, and serial antibody titers sometimes correlate with relapse risk and radiological activity (152, 153). Here, MOG is linked to neuromyelitis optica.