FKBP5 and post-traumatic stress disorder: Specifically, common variants in the FKBP5 gene are associated with higher FKBP5 protein expression, which leads to glucocorticoid receptor resistance and impaired negative feedback in the HPA axis, resulting in a slower return to baseline of stress-induced cortisol levels, which could potentially increase risk for the development of PTSD symptoms [21–23].