Admixture Mapping of Subclinical Atherosclerosis and Subsequent Clinical Events Among African Americans in 2 Large Cohort Studies

Background-Local ancestry may contribute to the disproportionate burden of subclinical and clinical cardiovascular disease among admixed African Americans compared with other populations, suggesting a rationale for admixture mapping. Methods and Results-We estimated local European ancestry (LEA) using Local Ancestry inference in adMixed Populations using Linkage Disequilibrium method (LAMP-LD) and evaluated the association with common carotid artery intima-media thickness (cCIMT) using multivariable linear regression analysis among 1554 African Americans from MESA (Multi-Ethnic Study of Atherosclerosis). We conducted secondary analysis to examine the significant cCIMT-LEA associations with clinical cardiovascular disease events. We observed genome-wide significance in relation to cCIMT association with the SERGEF gene (secretion-regulating guanine nucleotide exchange factor; beta=0.0137; P=2.98x10(-4)), also associated with higher odds of stroke (odds ratio=1.71; P=0.02). Several regions, in particular CADPS gene (Ca2+-dependent secretion activator 1) region identified in MESA, were also replicated in the ARIC cohort (Atherosclerosis Risk in Communities). We observed other cCIMT-LEA regions associated with other clinical events, most notably the regions harboring CKMT2 gene (creatine kinase, mitochondrial 2) and RASGRF2 gene (Ras protein-specific guanine nucleotide-releasing factor 2) with all clinical events except stroke, the LRRC3B gene (leucine-rich repeat containing 3B) with myocardial infarction, the PRMT3 gene (protein arginine methyltransferase 3) with stroke, and the LHFPL2 gene (lipoma high mobility group protein I-C fusion partner-like 2) with hard and all coronary heart disease. Conclusions-We identified several novel LEA regions, in addition to previously identified genetic variations, associated with cCIMT and cardiovascular disease events among African Americans.