For example, PTSD and depression have been associated with DNAm changes in blood and buccal cells at genes involved in glucocorticoid functioning, such as the FKBP prolyl isomerase 5 (FKBP5) and the nuclear receptor subfamily 3 group C member 1 (NR3C1)15–19. This evidence concerns the gene NR3C1 and major depressive disorder.