title: Associations of adiponectin with individual European ancestry in African Americans: the Jackson Heart Study.
abstract: BACKGROUND
  Compared with European Americans, African Americans (AAs) exhibit lower levels of the cardio-metabolically protective adiponectin even after accounting for adiposity measures. Because few studies have examined in AA the association between adiponectin and genetic admixture, a dense panel of ancestry informative markers (AIMs) was used to estimate the individual proportions of European ancestry (PEA) for the AAs enrolled in a large community-based cohort, the Jackson Heart Study (JHS). We tested the hypothesis that plasma adiponectin and PEA are directly associated and assessed the interaction with a series of cardio-metabolic risk factors.
  
  
  METHODS
  Plasma specimens from 1439 JHS participants were analyzed by ELISA for adiponectin levels. Using pseudo-ancestral population genotype data from the HapMap Consortium, PEA was estimated with a panel of up to 1447 genome-wide preselected AIMs by a maximum likelihood approach. Interaction assessment, stepwise linear and cubic multivariable-adjusted regression models were used to analyze the cross-sectional association between adiponectin and PEA.
  
  
  RESULTS
  Among the study participants (62% women; mean age 48 ± 12 years), the median (interquartile range) of PEA was 15.8 (9.3)%. Body mass index (BMI) (p = 0.04) and insulin resistance (p = 0.0001) modified the association between adiponectin and PEA. Adiponectin was directly and linearly associated with PEA (β = 0.62 ± 0.28, p = 0.03) among non-obese (n = 673) and insulin sensitive participants (n = 1141; β = 0.74 ± 0.23, p = 0.001), but not among those obese or with insulin resistance. No threshold point effect was detected for non-obese participants.
  
  
  CONCLUSIONS
  In a large AA population, the individual proportion of European ancestry was linearly and directly associated with plasma adiponectin among non-obese and non insulin-resistant participants, pointing to the interaction of genetic and metabolic factors influencing adiponectin levels.
authors.affiliation: Department of Epidemiology and Biostatistics, Indiana University School of Public Health - Bloomington Bloomington, IN, USA.
authors.forename: Aurelian
authors.initials: A
authors.lastname: Bidulescu
authors.affiliation: Department of Urology, University of California San Francisco, CA, USA.
authors.forename: Shweta
authors.initials: S
authors.lastname: Choudhry
authors.affiliation: Jackson Heart Study, University of Mississippi Medical Center Jackson, MS, USA.
authors.forename: Solomon K
authors.initials: SK
authors.lastname: Musani
authors.affiliation: Department of Health Sciences, Jackson State University Jackson, MS, USA.
authors.forename: Sarah G
authors.initials: SG
authors.lastname: Buxbaum
authors.affiliation: Jackson Heart Study, University of Mississippi Medical Center Jackson, MS, USA.
authors.forename: Jiankang
authors.initials: J
authors.lastname: Liu
authors.affiliation: National Human Genome Research Institute, National Institutes of Health Bethesda, MD, USA.
authors.forename: Charles N
authors.initials: CN
authors.lastname: Rotimi
authors.affiliation: Jackson Heart Study, University of Mississippi Medical Center Jackson, MS, USA.
authors.forename: James G
authors.initials: JG
authors.lastname: Wilson
authors.affiliation: Jackson Heart Study, University of Mississippi Medical Center Jackson, MS, USA.
authors.forename: Herman A
authors.initials: HA
authors.lastname: Taylor
authors.affiliation: National Heart Lung and Blood Institute, National Institutes of Health Bethesda, MD, USA.
authors.forename: Gary H
authors.initials: GH
authors.lastname: Gibbons
keywords: African Americans; adiponectin; cohort study; individual European ancestry; insulin resistance; minorities; obesity