The aims of the present study were a) to analyze the presence of anti-MOG antibodies in an independent blinded cohort of patients with NMO/NMOSD and multiple sclerosis (MS) using the previously described cell-based assay (CBA) [18], b) to correlate antibody findings to clinical and magnetic resonance imaging (MRI) parameters of MOG-seropositive and AQP4-seropositive NMO patients and NMO patients with no detectable antibodies, and c) to characterize the long-term clinical outcome of the MOG-seropositive patients. Here, AQP4 is linked to multiple sclerosis.