MOG and CNS demyelination: An earlier report suggested that these antibodies occur in 23/120 (19%) patients with MOGAD and in 2/114 (1.7%) patients with seronegative demyelinating diseases and are not clinically relevant.27 A more recent study identified MOG-IgA in 3/50 (6%) patients with seronegative CNS demyelination and suggested they may be a useful diagnostic marker,28 but this requires further study.