The possible involvement of the D2–5-HT2A heterodimer in schizophrenia was proposed by studies on the hallucinogenic 5-HT2A agonists showing that they probably induce a conformational state of the 5HT2A protomer different from the one produced by serotonin, leading to facilitating allosteric interactions with the D2 partner [171]. The gene discussed is HTR2A; the disease is schizophrenia.