Pituitary adenylate cyclase-activating polypeptide (PACAP, ADCYAP1) dysregulation has been associated with multiple stress-related psychopathologies (Kormos and Gaszner, 2013; Hammack and May, 2015; Lutfy and Shankar, 2019) and we and others have reported that a single nucleotide polymorphism (SNP) in the PAC1 receptor gene (ADCYAP1R1 rs2267735) as well as circulating PACAP levels were associated with post-traumatic stress disorder (PTSD; Ressler et al., 2011). This evidence concerns the gene ADCYAP1 and post-traumatic stress disorder.