In particular, Adcyap1 encodes pituitary adenylate cyclase activating polypeptide (PACAP), a critical sex-specific and oestrogen-dependent regulator of the stress response58 which has been associated with sex-specific anxiety-related behaviour in rodents39 and female-specific risk for PTSD in humans40. Here, ADCYAP1 is linked to post-traumatic stress disorder.