title: European ancestry as a risk factor for atrial fibrillation in African Americans.
abstract: BACKGROUND
  Despite a higher burden of standard atrial fibrillation (AF) risk factors, African Americans have a lower risk of AF than whites. It is unknown whether the higher risk is due to genetic or environmental factors. Because African Americans have varying degrees of European ancestry, we sought to test the hypothesis that European ancestry is an independent risk factor for AF.
  
  
  RESULTS
  We studied whites (n=4543) and African Americans (n=822) in the Cardiovascular Health Study (CHS) and whites (n=10 902) and African Americans (n=3517) in the Atherosclerosis Risk in Communities (ARIC) Study (n=3517). Percent European ancestry in African Americans was estimated with 1747 ancestry informative markers from the Illumina custom ITMAT-Broad-CARe array. Among African Americans without baseline AF, 120 of 804 CHS participants and 181 of 3517 ARIC participants developed incident AF. A meta-analysis from the 2 studies revealed that every 10% increase in European ancestry increased the risk of AF by 13% (hazard ratio, 1.13; 95% confidence interval, 1.03 to 1.23; P=0.007). After adjustment for potential confounders, European ancestry remained a predictor of incident AF in each cohort alone, with a combined estimated hazard ratio for each 10% increase in European ancestry of 1.17 (95% confidence interval, 1.07 to 1.29; P=0.001). A second analysis using 3192 ancestry informative markers from a genome-wide Affymetrix 6.0 array in ARIC African Americans yielded similar results.
  
  
  CONCLUSIONS
  European ancestry predicted risk of incident AF. Our study suggests that investigating genetic variants contributing to differential AF risk in individuals of African versus European ancestry will be informative.
authors.affiliation: Electrophysiology Section, Division of Cardiology, University of California, San Francisco, 500 Parnassus Ave, MUE 434, San Francisco, CA 94143-1354, USA. marcusg@medicine.ucsf.edu
authors.forename: Gregory M
authors.initials: GM
authors.lastname: Marcus
authors.forename: Alvaro
authors.initials: A
authors.lastname: Alonso
authors.forename: Carmen A
authors.initials: CA
authors.lastname: Peralta
authors.forename: Guillaume
authors.initials: G
authors.lastname: Lettre
authors.forename: Eric
authors.initials: E
authors.lastname: Vittinghoff
authors.forename: Steven A
authors.initials: SA
authors.lastname: Lubitz
authors.forename: Ervin R
authors.initials: ER
authors.lastname: Fox
authors.forename: Yamini S
authors.initials: YS
authors.lastname: Levitzky
authors.forename: Reena
authors.initials: R
authors.lastname: Mehra
authors.forename: Kathleen F
authors.initials: KF
authors.lastname: Kerr
authors.forename: Rajat
authors.initials: R
authors.lastname: Deo
authors.forename: Nona
authors.initials: N
authors.lastname: Sotoodehnia
authors.forename: Meggie
authors.initials: M
authors.lastname: Akylbekova
authors.forename: Patrick T
authors.initials: PT
authors.lastname: Ellinor
authors.forename: Dina N
authors.initials: DN
authors.lastname: Paltoo
authors.forename: Elsayed Z
authors.initials: EZ
authors.lastname: Soliman
authors.forename: Emelia J
authors.initials: EJ
authors.lastname: Benjamin
authors.forename: Susan R
authors.initials: SR
authors.lastname: Heckbert
mesh_terms: D001741:Black or African American / Q000235:genetics*; D000368:Aged; D001281:Atrial Fibrillation / Q000453:epidemiology / Q000235:genetics* / Q000503:physiopathology; D005260:Female; D055106:Genome-Wide Association Study; D006801:Humans; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D044465:White People / Q000235:genetics*