FKBP5 and major depressive disorder: The FKBP5 gene is involved in the regulation of the hypothalamic-pituitary-adrenal (HPA) axis, which is a major stress - response system in the body.Polymorphisms rs1360780 and rs3800373 in the FKBP5 gene were associated with suicidal events in adolescents with treatment-resistant depression (Brent et al., 2010).