MOG and myeloid sarcoma: Although early studies found that 41% of multiple sclerosis (MS) patients had anti-MOG antibodies in serum, as did patients with non-MS neurologic disease and healthy patients [12,13,14,15,16,17], it is now known that anti-MOG antibodies are rare in patients with typical MS phenotypes [11] and that anti-MOG syndromes are clinically distinct entities from MS.