[Multiple sclerosis and migration].

Multiple sclerosis, original primary demyelination in the central nervous system, is a disease of as yet unknown cause. Epidemiologic research may contribute to the clarification of this problem. Migration studies have proven that susceptibility to multiple sclerosis is associated with ethnic origin and environment, and that the critical age for the disease development is till 15 years. In Croatia, emigrating inhabitants of Gorski Kotar, a region with high exposure to this disease, carry the risk of multiple sclerosis development, provided that have emigrated after adolescence.