Project description:The goal of this study was to identify genetic predictors of response to rate control therapy in patients with AF. We conducted a genome-wide association study (GWAS) focusing on subjects with a history of atrial fibrillation. Rate control therapy for AF uses a range of drugs (beta-adrenergic receptor blockers, calcium channel blockers, and digitalis) to depress conduction through the AV node, thereby preventing rapid rates and minimizing symptoms. In large groups of patients, such as the Vanderbilt AF Registry (a clinical and genetic repository with over 1200 patients with ECG-confirmed AF) from which these study subjects were drawn, approximately 5% display failure of aggressive AV nodal-blocking therapy to control ventricular rate. In these patients, interruption of the AV node by ablation and pacemaker implantation are necessary for adequate rate control. Study cases were individuals who underwent AV node ablation and pacemaker implantation after combined therapy with 3 AV nodal-blocking agents was ineffective in rate control. Controls for this study were individuals who met standardized rate-control efficacy criteria (as described in AFFIRM study, Wyse et al, NEJM 2002; PMID: <a href="http://www.ncbi.nlm.nih.gov/pubmed/12466506" target="_blank">12466506</a>) for optimal rate control with 2 or fewer AV nodal-blocking agents. Two additional groups were genotyped by RIKEN: An additional group of patients with AF as well as subjects undergoing cardiac surgery in whom AF did not occur post-operatively. All study participants were recruited and treated/evaluated at Vanderbilt University Medical Center. This study was conducted by the Pharmacogenomics of Arrhythmia Therapy subgroup of the Pharmacogenetics Research Network, a nationwide collaboration of scientists studying the genetic contributions to drug response variability. Genotyping was performed by the RIKEN research institute in Japan using the Illumina 610 Quad Beadchip platform.

Project description:BACKGROUND: Obesity is associated with changes in fat cell gene expression and metabolism. What drives these changes is not well understood. We aimed to explore fat cell epigenetics, i.e., DNA methylation, as one mediator of gene regulation, in obese women. The global DNA methylome for abdominal subcutaneous fat cells was compared between 15 obese case (BMI 41.4?±?4.4 kg/m(2), mean?±?SD) and 14 never-obese control women (BMI 25.2?±?2.5 kg/m(2)). Global array-based transcriptome analysis was analyzed for subcutaneous white adipose tissue (WAT) from 11 obese and 9 never-obese women. Limma was used for statistical analysis. RESULTS: We identified 5529 differentially methylated DNA sites (DMS) for 2223 differentially expressed genes between obese cases and never-obese controls (false discovery rate <5 %). The 5529 DMS displayed a median difference in beta value of 0.09 (range 0.01 to 0.40) between groups. DMS were under-represented in CpG islands and in promoter regions, and over-represented in open sea-regions and gene bodies. The 2223 differentially expressed genes with DMS were over-represented in key fat cell pathways: 31 of 130 (25 %) genes linked to "adipogenesis" (adjusted P?=?1.66?×?10(-11)), 31 of 163 (19 %) genes linked to "insulin signaling" (adjusted P?=?1.91?×?10(-9)), and 18 of 67 (27 %) of genes linked to "lipolysis" (P?=?6.1?×?10(-5)). In most cases, gene expression and DMS displayed reciprocal changes in obese women. Furthermore, among 99 candidate genes in genetic loci associated with body fat distribution in genome-wide association studies (GWAS); 22 genes displayed differential expression accompanied by DMS in obese versus never-obese women (P?=?0.0002), supporting the notion that a significant proportion of gene loci linked to fat distribution are epigenetically regulated. CONCLUSIONS: Subcutaneous WAT from obese women is characterized by congruent changes in DNA methylation and expression of genes linked to generation, distribution, and metabolic function of fat cells. These alterations may contribute to obesity-associated metabolic disturbances such as insulin resistance in women.

Dataset Information

A Genome-Wide Association Study in Patients Experiencing Drug-Induced Long-QT Syndrome and/or Torsades de Pointes; A Collaboration Between the NIH Pharmacogenomics Research Network and the RIKEN Yokohama Institute Center for Genomic Medicine

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