In the HC trial described above [46], greater responses to HC were seen in participants with higher lifetime PTSD symptoms and greater glucocorticoid sensitivity prior to treatment, suggesting that symptom severity, glucocorticoid receptor sensitivity, and the modulating chaperone protein FKBP5 may account for differences in response to glucocorticoids [58]. This evidence concerns the gene FKBP5 and post-traumatic stress disorder.