FKBP5 and post-traumatic stress disorder: 2013, Szczepankiewicz et al. 2014, Q. Wang et al. 2018, Zannas et al. 2016). FKBP5 regulates glucocorticoid receptor sensitivity and is implicated in stress reactivity, especially in individuals with early‐life trauma (Q. Wang et al. 2018). Its functional variants such as rs1360780 are associated with increased psychiatric vulnerability in gene–environment interaction models (Hawn et al. 2019). NR3C1, encoding the glucocorticoid receptor, modulates transcriptional responses to stress hormones and is dysregulated in both MDD and PTSD (Sheerin et al. 2020).