ADCYAP1 and schizophrenia: Human genetic and gene targeting studies undertaken by us and others have suggested that pituitary adenylate cyclase-activating polypeptide (PACAP) is a risk factor for psychiatric disorders, such as schizophrenia (Hashimoto et al., 2001, 2007; Ressler et al., 2011; Hazama et al., 2014).