In contrast, low titres of MOG-IgG are less specific and are also seen in a small proportion of patients with MS, other neurological diseases, and healthy individuals.2, , –5 The diagnosis of MOGAD can therefore be made based on key clinical features alone if the MOG-IgG result is clearly positive, whereas in the case of a low positive MOG-IgG result additional supporting clinical or magnetic resonance imaging (MRI) features are required. The gene discussed is MOG; the disease is myeloid sarcoma.