Genetic admixture is associated with plasma hemostatic factor levels in self-identified African Americans and Hispanics: the Multi-Ethnic Study of Atherosclerosis

. Background: Epidemiologic studies report that self-identified African Americans typically have higher hemostatic factor levels than do self-identified Caucasians or Hispanics.Objective: To enhance understanding of phenotypic variation in hemostatic factor levels by race/ethnicity, we evaluated the relationship between genetic ancestry and hemostatic factor levels among Multi-Ethnic Study of Atherosclerosis (MESA) study participants.Patients/methods: Our sample included 712 African American and 701 Hispanic men and women aged 45 to 84 years. Individual global ancestry was estimated from 199 genetic markers using STRUCTURE. Linear regression models were used to evaluate the relationship between ancestry and hemostatic factor levels, adjusting for age, gender, education, income and study site.Results: Among African Americans, mean +/- standard deviation (SD) ancestry was estimated as 79.9% +/- 15.9% African and 20.1% +/- 15.9% European. Each SD (16%) greater African ancestry was associated with 2.1% higher fibrinogen levels (P = 0.007) and 3.5% higher plasminantiplasmin (PAP) levels (P = 0.02). Ancestry among African Americans was not related to levels of factor (F)VIII or D-dimer. Mean +/- SD estimated ancestry among Hispanics was 48.3% +/- 23.8% Native American, 38.8% +/- 21.9% European, and 13.0% +/- 8.9% African. In Hispanics, each SD (19%) greater African ancestry was associated with 2.7% higher fibrinogen levels (P = 0.009) and 7.9% higher FVIII levels (P = 0.0002). In Hispanics, there was no relation between African ancestry and D-dimer or PAP levels, or between European ancestry and hemostatic factor levels.Conclusions: Greater African ancestry among African Americans and Hispanics was associated with higher levels of several hemostatic factors, notably fibrinogen. These results suggest that genetic heterogeneity contributes, albeit modestly, to racial/ethnic differences in hemostatic factor levels.