Epidemiology of multiple sclerosis in U.S. veterans: V. Ancestry and the risk of multiple sclerosis

Self-reported ancestry data for the U.S. population from the 1980 decennial census and multiple sclerosis (MS) risk data derived from a large series of World War II white male veterans with MS and matched controls were aggregated on a state level and analyzed to determine the relationship between ancestry and MS risk. A significant portion of the state-by-state variation in MS risk is explainable statistically by differences in ancestry among state populations, even when geographic latitude is included in analyses. In the main, Swedish and other Scandinavian ancestry is most consistently associated with places with increased MS risk. In some analyses, Italian, French, and (to a lesser extent) Scottish ancestries are also associated with increased risk, whereas English and Dutch ancestries are each associated with decreased risk, but most of these non-Scandinavian correlations may reflect predominantly geography per se. These findings provide evidence that ancestry of the resident population, a confounded measure of genetic susceptibility and cultural environment, is part of the complicated picture of MS as a disease of place.