We performed a thorough diagnostic workup to exclude alternative inflammatory or autoimmune conditions, including Lyme disease (negative serology), MS, neuromyelitis optica (NMO), myelin oligodendrocyte glycoprotein (MOG) antibody-associated disorders (negative antibody tests), mitochondrial disorders (absence of pathogenic mitochondrial DNA mutations), and Fabry disease (normal alpha-galactosidase activity). The gene discussed is MOG; the disease is neuromyelitis optica.