Chronic Fatigue Syndrome and DNA Hypomethylation of the Glucocorticoid Receptor Gene Promoter 1F Region: Associations With Hypothalamic-Pituitary-Adrenal Axis Hypofunction and Childhood Trauma. Vangeel E, Van Den Eede F, Hompes T, Izzi B, Del Favero J, Moorkens G, Lambrechts D, Freson K, Claes S. Psychosom Med. 2015 Jul 30. [Epub ahead of print] http://www.ncbi.nlm.nih.gov/pubmed/26230484 Abstract OBJECTIVES: Chronic fatigue syndrome (CFS) has been associated with hypothalamic-pituitary-adrenal axis hypofunction and enhanced glucocorticoid receptor (GR) sensitivity. In addition, childhood trauma is considered a major risk factor for the syndrome. This study examines DNA methylation of the GR gene (NR3C1) in CFS and associations with childhood sexual and physical trauma. METHODS: Quantification of DNA methylation within the 1F promoter region of NR3C1 was performed in 76 female patients (46 with no/mild and 30 with moderate/severe childhood trauma) and 19 healthy controls using Sequenom EpiTYPER. Further, we examined the association of NR3C1-1F promoter methylation the low-dose (0.5 mg) dexamethasone/corticotropin-releasing factor test outcomes in a subset of the study population. Mann-Whitney U tests and Spearman correlations were used for statistical analyses. RESULTS: Overall NR3C1-1F DNA methylation was lower in patients with CFS than in controls. After cytosine guanine dinucleotide (CpG)-specific analysis, CpG_1.5 remains significant after Bonferroni correction (adjusted p = .0014). Within the CFS group, overall methylation (? = 0.477, p = .016) and selective CpG units (CpG_1.5: ? = 0.538, p = .007; CpG_12.13: ? = 0.448, p = .025) were positively correlated with salivary cortisol after dexamethasone administration. There was no significant difference in NR3C1-1F methylation between traumatized and nontraumatized patients. CONCLUSIONS: We found evidence of NR3C1 promoter hypomethylation in female patients with CFS and the functional relevance of these differences was consistent with the hypothalamic-pituitary-adrenalaxis hypofunction hypothesis (GR hypersuppression). However, we found no evidence of an additional effect of childhood trauma on CFS via alterations in NR3C1 methylation.