It is well known that intracellular signalling, such as Erk and Akt signalling, plays important roles in the pathophysiology of mood disorders and cognitive impairments [48] since D2R, 5-HT1A, and 5-HT7R regulate both Akt and Erk [18,49,50,51,52,53] signalling [18,49,50,51,52,53]. The gene discussed is DRD2; the disease is mood disorder.