FKBP5 and post-traumatic stress disorder: Patients with PTSD and animal models of PTSD display dysregulations of the HPA axis on several levels, such as blood glucocorticoid and ACTH concentration, expression of GR receptors in many brain regions as well as GR receptor modulator glucocorticoid sensitive co-chaperone FK506-binding protein 5 (FKBP5) (Yehuda, 2009; Mehta et al., 2011; Knox et al., 2012; Laukova et al., 2014).