Epigenome-Wide Association Study of Fasting Measures of Glucose, Insulin, and HOMA-IR in the Genetics of Lipid Lowering Drugs and Diet Network Study

  1. Donna K. Arnett2
  1. 1Department of Biostatistics, Section on Statistical Genetics, University of Alabama at Birmingham, Birmingham, AL
  2. 2Department of Epidemiology, University of Alabama at Birmingham, Birmingham, AL
  3. 3Hudson Alpha Institute for Biotechnology, Huntsville, AL
  4. 4Department of Medicine, Vanderbilt University, Nashville, TN
  5. 5Jean Mayer USDA Human Nutrition Research Center on Aging, Tufts University, Medford, MA
  1. Corresponding author: Bertha Hidalgo, bhidalgo{at}uab.edu.


Known genetic susceptibility loci for type 2 diabetes (T2D) explain only a small proportion of heritable T2D risk. We hypothesize that DNA methylation patterns may contribute to variation in diabetes-related risk factors, and this epigenetic variation across the genome can contribute to the missing heritability in T2D and related metabolic traits. We conducted an epigenome-wide association study for fasting glucose, insulin, and homeostasis model assessment of insulin resistance (HOMA-IR) among 837 nondiabetic participants in the Genetics of Lipid Lowering Drugs and Diet Network study, divided into discovery (N = 544) and replication (N = 293) stages. Cytosine guanine dinucleotide (CpG) methylation at ∼470,000 CpG sites was assayed in CD4+ T cells using the Illumina Infinium HumanMethylation 450 Beadchip. We fit a mixed model with the methylation status of each CpG as the dependent variable, adjusting for age, sex, study site, and T-cell purity as fixed-effects and family structure as a random-effect. A Bonferroni corrected P value of 1.1 × 10−7 was considered significant in the discovery stage. Significant associations were tested in the replication stage using identical models. Methylation of a CpG site in ABCG1 on chromosome 21 was significantly associated with insulin (P = 1.83 × 10−7) and HOMA-IR (P = 1.60 × 10−9). Another site in the same gene was significant for HOMA-IR and of borderline significance for insulin (P = 1.29 × 10−7 and P = 3.36 × 10−6, respectively). Associations with the top two signals replicated for insulin and HOMA-IR (P = 5.75 × 10−3 and P = 3.35 × 10−2, respectively). Our findings suggest that methylation of a CpG site within ABCG1 is associated with fasting insulin and merits further evaluation as a novel disease risk marker.

  • Received July 16, 2013.
  • Accepted October 7, 2013.

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  1. Diabetes vol. 63 no. 2 801-807
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