In preclinical studies, Fkbp5 expression levels modulated alcohol intake and withdrawal severity, with Fkbp5 knockout mice increasing alcohol intake and exhibiting sensitivity to alcohol withdrawal.70,92 In humans, a study has linked a SNP genotype of FKBP5 and the presence of poor child-parent relationships to problematic drinking behavior.93 Collectively, ELS exposure leads to epigenetic changes at genes that alter HPA axis function, and those changes, along with genetic variations, may increase the risk for the development of PTSD. Here, FKBP5 is linked to post-traumatic stress disorder.