NR3C1 and major depressive disorder: DNA methylation studies of the glucocorticoid receptor gene in post-traumatic stress disorder (PTSD) and immunity have highlighted the role of NR3C1 DNA methylation in HPA axis dysregulation in major depressive disorder (MDD), indicating that epigenetic modifications of NR3C1 may affect stress reactivity and contribute to the pathophysiology of MDD [61].