Glucocorticoid receptor gene (NR3C1) DNA methylation in association with trauma, psychopathology, transcript expression, or genotypic variation: A systematic review.

The glucocorticoid receptor gene (NR3C1) is a critical component of the stress response system. Cytosine methylation of NR3C1 has been repeatedly associated with trauma and mental disorders, including major depression, post-traumatic stress disorder, anxiety, and personality disorders, suggesting that NR3C1 methylation may play a role in stress-related psychopathology. We systematically reviewed 55 studies examining NR3C1 DNA methylation in association with trauma exposure, psychopathology, gene expression, and/or common genetic variants. Overall, a number of NR3C1 CpG sites were significantly associated with trauma or psychopathology, but significant findings were often inconsistent across studies. This lack of consistency is likely influenced by significant methodological variability - experimentally and analytically - across studies. Selected common genetic variants show no significant effect on NR3C1 CpG methylation. In contrast, there was ample evidence linking increased methylation of NR3C1 to reduced expression of this gene. The inverse association between methylation and gene expression shown across eight out of ten studies supports the notion that methylation in the promoter region of NR3C1 is associated with transcriptional silencing.