Hum Genet DOI 10.1007/s00439-007-0353-zORIGINAL INVESTIGATION Genetic admixture, adipocytokines, and adiposity in Black Americans: the Health, Aging, and Body Composition study

Abstract Adipocytokines are a subset of cytokines pro-duced by adipose tissue and are associated with risk of type II diabetes and atherosclerosis. Levels of adipocytokines diVer between Black and White Americans, even after adjustment for diVerences in adiposity, diseases associated with adipocytokines including type 2 diabetes and cardio-vascular disease, and general socioeconomic status indica-tors such as income. We used a series of ancestry informative markers to estimate genetic ancestry in a popu-lation-based study of older Black Americans, and examined the association between genetic ancestry and adipocytokines and soluble receptors to help determine which of these may be most amenable to admixture mapping. We typed 35 ancestry informative markers in 1,241 self-reported Black Americans with available DNA from the Health, Aging, and Body Composition (Health ABC) study with available DNA and used a maximum likelihood approach to estimate per-cent European ancestry. We used linear regression models to determine the association between these adipocytokines and percent ancestry, and staged models to examine whether adi-posity or other measures aVected the associations of genetic ancestry and adipocytokines. Mean European ancestry was 22.3 § 15.9%. In multivariate adjusted models, the strongest associations observed were between higher European ances-try and interleukin-6 soluble receptor (IL-6 SR), C-reactive protein (CRP), and adiponectin levels, with interleukin-2 soluble receptor (IL-2 SR) and soluble tumor necrosis factor receptor II (TNF- SR II) also showing more modest but signiWcant associations. The association with adiponectin became stronger after adjustment for adiposity. These novel Wndings suggest that admixture mapping may identify genetic factors inXuencing the levels of IL-6 SR, CRP, IL-2 SR, and adiponectin