It is characterized by the presence of GFAP-immunoglobulin G (GFAP-IgG), most specifically detected in cerebrospinal fluid (CSF), and presents clinically with acute or subacute meningoencephalitis symptoms such as fever, headache, altered mental status, seizures, and occasionally myelitis or optic neuritis (3, 4). The gene discussed is GFAP; the disease is optic neuritis.