Epigenome-wide Association Study of Obesity Susceptibility in Human Twins

The purpose of the current study was to use an epigenome-wide association approach (EWAS) to identify a potential DNA methylation alterations associated with obesity using twins discordant on obesity status. Buccal cells (from a cheek swab) were used as a purified marker cell for the epigenetic analysis. Analysis of differential DNA methylation regions (DMRs) was used to identify epigenetic associations with metabolic and dietary measures in obesity parameters discordant twins. An edgeR analysis provided a DMR signature with p<1e-04, but a false discovery rate analysis demonstrated a lack of significance due to low sample size and known multivariant origins of obesity. The Washington State Twin Registry (WSTR) facilitated the collection and shipment of buccal cell samples from twins with and without obesity. Methylated DNA immunoprecipitation (MeDIP) was performed on the buccal cell DNA samples. The MeDIP was followed by DNA sequencing (MeDIP-Seq). Differential DNA methylation regions (DMRs) were identified for the male and female homozygous, heterozygous, and all twin pairs. Please note that several samples do not have an associated processed data file. These samples were not used in the analyses prepared for publication due to QC or discordance issues. They are included in this submission for completeness.