The significance of these variations is linked to the etiology of many psychiatric diseases, including psychoses; additionally, they can also influence the pharmacodynamic effects of these drugs, including adverse effects such as weight gain and other metabolic adverse effects [108,109], as well as the therapeutic response to APC agents, which constitutes both positive and negative symptoms of schizophrenia, especially polymorphism (−759 C/T) [110]. This evidence concerns the gene APC and psychiatric disorder.