title: Promoter methylation of glucocorticoid receptor gene is associated with subclinical atherosclerosis: A monozygotic twin study.
abstract: OBJECTIVE
  Endothelial dysfunction assessed by brachial artery flow-mediated dilation (FMD) is a marker of early atherosclerosis. Glucocorticoid receptor gene (NR3C1) regulates many biological processes, including stress response, behavioral, cardiometabolic and immunologic functions. Genetic variants in NR3C1 have been associated with atherosclerosis and related risk factors. This study investigated the association of NR3C1 promoter methylation with FMD, independent of genetic and family-level environmental factors.
  
  
  METHODS
  We studied 84 middle-aged, male-male monozygotic twin pairs recruited from the Vietnam Era Twin Registry. Brachial artery FMD was measured by ultrasound. DNA methylation levels at 22 CpG residues in the NR3C1 exon 1F promoter region were quantified by bisulfite pyrosequencing in genomic DNA isolated from peripheral blood leukocytes. Co-twin control analyses were conducted to examine the association of methylation variation with FMD, adjusting for smoking, physical activity, body mass index, lipids, blood pressure, fasting glucose, and depressive symptoms. Multiple testing was corrected using the false discovery rate.
  
  
  RESULTS
  Mean methylation level across the 22 studied CpG sites was 2.02%. Methylation alterations at 12 out of the 22 CpG residues were significantly associated with FMD. On average, a 1% increase in the intra-pair difference in mean DNA methylation was associated with 2.83% increase in the intra-pair difference in FMD (95% CI: 1.46-4.20; P < 0.0001) after adjusting for risk factors and multiple testing.
  
  
  CONCLUSIONS
  Methylation variation in NR3C1 exon 1F promoter significantly influences subclinical atherosclerosis, independent of genetic, early family environmental and other risk factors.
authors.affiliation: Department of Epidemiology, School of Public Health and Tropical Medicine, Tulane University, New Orleans, LA, USA. Electronic address: jzhao5@tulane.edu.
authors.forename: Jinying
authors.initials: J
authors.lastname: Zhao
authors.affiliation: Department of Epidemiology, School of Public Health and Tropical Medicine, Tulane University, New Orleans, LA, USA.
authors.forename: Qiang
authors.initials: Q
authors.lastname: An
authors.affiliation: Seattle Epidemiologic Research and Information Center, VA Puget Sound Health Care System, Seattle, WA, USA; Department of Epidemiology, University of Washington, Seattle, WA, USA.
authors.forename: Jack
authors.initials: J
authors.lastname: Goldberg
authors.affiliation: Department of Medicine, School of Medicine, Emory University, Atlanta, GA, USA.
authors.forename: Arshed A
authors.initials: AA
authors.lastname: Quyyumi
authors.affiliation: Department of Medicine, School of Medicine, Emory University, Atlanta, GA, USA; Department of Epidemiology, School of Public Health, Emory University, Atlanta, GA, USA.
authors.forename: Viola
authors.initials: V
authors.lastname: Vaccarino
mesh_terms: D000368:Aged; D058070:Asymptomatic Diseases; D050197:Atherosclerosis / Q000235:genetics*; D001483:Base Sequence; D001786:Blood Glucose / Q000032:analysis; D001794:Blood Pressure; D015992:Body Mass Index; D001916:Brachial Artery / Q000503:physiopathology; D015986:Confounding Factors, Epidemiologic; D018899:CpG Islands / Q000235:genetics; D019175:DNA Methylation; D003863:Depression / Q000453:epidemiology; D004200:Diseases in Twins / Q000235:genetics*; D005091:Exons / Q000235:genetics; D006801:Humans; D008055:Lipids / Q000097:blood; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D009043:Motor Activity; D011401:Promoter Regions, Genetic / Q000235:genetics*; D011965:Receptors, Glucocorticoid / Q000235:genetics*; D012042:Registries; D012307:Risk Factors; D012907:Smoking / Q000453:epidemiology; D014430:Twins, Monozygotic / Q000235:genetics*; D014481:United States / Q000453:epidemiology; D059289:Vascular Stiffness; D014664:Vasodilation
chemical_list: D001786:Blood Glucose; D008055:Lipids; D011965:Receptors, Glucocorticoid
keywords: DNA methylation; Monozygotic twins; NR3C1; Subclinical atherosclerosis