FKBP5 and post-traumatic stress disorder: However, it is important to note that studies in humans have revealed lower levels of FKBP5 and GR mRNA in the amygdala of suicide victims (Perez-Ortiz et al., 2012) and lower levels of FKBP5 mRNA in the blood of PTSD patients (Yehuda et al., 2009).