Changes in the Epigenetic Landscape of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome Reflect Systemic Dysfunctions
Purpose: ME/CFS is a lifelong debilitating disease that affects approximately 1% of the global population. Previous studies have identified dysfunctional activity in metabolic, immune and neurological pathways. The goal of this study is to identify ME/CFS specific variations in DNA methylation to determine whether the patient specific epigenetic patterns provide insight into the disease pathophysiology. Methods: DNA was extracted from the PBMCs of 10 ME/CFS patients and age/gender matched controls. After performing RRBS the sequence was aligned to hg19 genome using Bismark. The data was analyzed using first an ANOVA F test through DMAP in order to determine variation between the patient and control groups across 40-220bp fragments of the genome. Additional analysis was performed following a MethylKit pipeline, which analyzed the variation on a single CpG basis using a Fishers test. Results: From a total of 146,575 DMAP fragments we identified 76 differentially methylated fragments (P <0.05, Diff meth +/- 15%). A total of 31 were associated with gene regions (intronic/exonic). MethylKit analysis also identified a total of 394 differentially methylated cytosines (FDR corrected P <0.05, Diff meth +/- 15%) from a total of 196,172 individual analyzed cytosines, 91 of the statistically significant cytosines fell within gene regions. Comparison of both methylomes and regions where both the DMAP fragments and multiple MethylKit cytosines fell highlighted areas of the genome containing regulatory elements associated with metabolic and immune activity. Gene body pathway enrichment additionally identified immune metabolic and neurological related functions. Conclusions:  Our study represents the first investigation of ME/CFS patients using reduced representation bisulfite sequencing. We identified a number of major differences between patients that distinguished them from healthy controls. Our results identified a number of differentially methylated regulatory elements and gene bodies that highlight the disturbed pathophysiology in ME/CFS. In particular the large number of enriched neurotransmitter and neuropeptide reactome pathways highlighted a disturbed neurological pathophysiology in patients. Overall design: RRBS Analysis of 10 ME/CFS patients vs. Controls