Myelin Oligodendrocyte Glycoprotein Antibody Disease (MOG-AD) is a neuroimmune disorder that causes inflammation primarily in the optic nerve but can also affect the spinal cord and brain. MOG is a protein located on the surface of myelin sheaths in the central nervous system. MOG-AD is diagnosed through a test that looks for the level of MOG antibodies in the blood. The test should be given to any patient who has an inflammatory attack of the central nervous system. Because of the rare nature of the disorder, it is often misdiagnosed or not diagnosed at all.