Although our list of differentially methylated regions associated with CPA is comprehensive it is still possible that additional differentially methylated regulatory regions exist in these loci that were not discovered in our analysis. The small sample size could result in loss of power to detect additional significant correlations. In addition, the associations of differentially methylated regions and cytokine expression delineated here are probably an underestimation since we have used plasma cytokine levels rather than transcription rates as a measure of cytokine expression. There are many steps in between initiation of transcription at the promoter and cytokine levels in plasma. Unfortunately, the study design did not allow us to isolate high quality RNA because it was difficult to request that the subjects come to the lab for their blood perfusion, particularly with the chronic aggression group, resulting in a delay between cell harvest and RNA processing. In addition, DNA methylation and expression are fundamentally different measures of cell functional states. DNA methylation levels directly correspond to the number of cells with a methylated/unmethylated cytosine (as a state of methylation of an
