A significant reduction on DRD2 receptor availability (probably density) was observed in A1A2 group compared with A2A2 group.25 Bromocriptine, a DRD2 agonist, was effective to improve craving and anxiety only for alcoholics carrying A1 allele.26 The associations with DRD2 polymorphisms have been reported for many conditions including alcoholism,26,27 drug abuse,28,29 and obesity.30 These findings provide circumstantial evidence that the DRD2 polymorphism also play a role in smoking behavior, though the direct mechanism relating to the behavior remains to be elucidated. Here, DRD2 is linked to obesity due to melanocortin 4 receptor deficiency.