Changes in the composition and function of commensal microbes can trigger inflammation and abnormal immune activation, contributing to disorders such as multiple sclerosis (MS), neuromyelitis optica spectrum disorder (NMOSD), myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD), autoimmune encephalitis (AIE), neuropsychiatric lupus (NPSLE), and narcolepsy. This evidence concerns the gene MOG and autoimmune encephalitis.