The neuromyelitis optica study group (NEMOS; see www.nemos-net.de), founded in 2008 as a nation-wide network of primary, secondary, and tertiary care centers, seeks to broaden the understanding of NMOSD and clinically related (but pathogenetically distinct) disorders, such as myelin oligodendrocyte glycoprotein antibody-associated encephalomyelitis (MOG-EM; also termed MOG antibody-associated disease, MOGAD) [77, 134]. Here, MOG is linked to erythema multiforme.