DRD4 and obesity due to melanocortin 4 receptor deficiency: In this review, after a brief description of the DRD4, we will revise the current literature linking this receptor and DRD4 gene polymorphism to the development of drug addiction and aberrant ED, including binge eating behavior and obesity, describing the possible role played by the DRD4 in neural mechanisms implicated in these neuropsychiatric disorders.