Recent studies have suggested that TDLs may be a group of relatively independent diseases, or an early manifestation of demyelinating diseases, such as multiple sclerosis (MS), neuromyelitis optica spectrum disorder (NMOSD), acute disseminated encephalomyelitis (ADEM), myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) and clinically isolated syndrome (CIS) (13–15). The gene discussed is MOG; the disease is neuromyelitis optica.