PAC1 is a G-protein-coupled receptor activated by pituitary adenylate cyclase activating polypeptide (PACAP, Adcyap1), which is a potential schizophrenia susceptibility gene and whose loss of function in mice (PACAP−/−) showed several schizophrenia-related behaviors (Hashimoto et al., 2007). Here, ADCYAP1 is linked to schizophrenia.