MOG and multiple sclerosis: While this was not a problem for identification of multiple sclerosis, other groups contained diagnoses, which would have been interesting to identify separately, such as clinically isolated syndrome, which is associated with future multiple sclerosis risk,33 and myelin oligodendrocyte glycoprotein antibody disease, which is a separate disease entity.34 Lack of a specific diagnosis may also be because of insufficient follow-up time.