EPIDEMIOLOGY OF MULTIPLE-SCLEROSIS IN US VETERANS .6. POPULATION ANCESTRY AND SURNAME ETHNICITY AS RISK-FACTORS FOR MULTIPLE-SCLEROSIS

Previously, we studied the effect of population ancestry on the risk o f multiple sclerosis (MS) in US veterans of World War II, comparing by state 1980 US census ancestry data with MS case/control ratios. Here, the joint effects of population ancestry and surname-derived ethnicit y on MS risk are examined in the same series. Census data are used aga in to characterize the population ancestry of the state from which eac h subject entered active duty (EAD) - that is, the proportions of the populace reporting various ancestries - and subjects were also individ ually categorized into a single ethnic group, without knowledge of cas e/control status, based on surname. In this study population, categori zed ethnicity was strongly correlated with population ancestry, as exp ected. Although univariate analyses showed statistically significant a ssociations between MS risk and several surname-derived ethnicities an d ethnic groups, when residence at EAD was accounted for as well, ther e was almost no ethnic variation in MS risk. A logistic regression ana lysis further showed that variations in MS risk are associated most st rongly with latitude and population ancestry group; in particular, sub jects who entered military service from states with higher proportions of Swedish or French ancestry had higher risks of MS. After adjustmen t for characteristics of place, the only significant individual ethnic ity factor found was Southern European ethnicity. In general, we concl ude that an individual's ethnicity seems to be of less relative import ance in determining MS risk than is the population ancestry of the sta te of EAD. These findings underscore the fact that MS is a disease of place, with 'place' including not only attributes of the locale (e.g., latitude), but also of its populace (e.g., ancestry).