The relevance between dopamine D3 receptor gene variations and drug addiction

Drug addiction is characterized by impairment of reward, compulsive behavior and inhibitory control deficits. Addiction genetic studies are focused on identifying the candidate genes responsible for the disease. However studies performed in different populations reveal different and sometimes conflicting results. In this study we aimed to determine the association of dopamine DRD3 receptor gene polymorphism and drug addiction in Turkish population. The patient group included 126 addicts diagnosed according to DSM-IV criteria. The results were compared to 100 individuals with no history of addiction. The gene frequencies were tested with Hardy-Weinberg equilibrium. Socio-demographic data including educational level, marital status and occupation were also evaluated. The frequencies of A1 homozygote individuals were 46%, A1 and A2 heterozygotes were 41.6% and A2 homozygotes were 12.7%, while they were respectively 46%, 43% and 11% in controls. According to the overall results, no statistically significant difference in DRD3 polymorphism was observed between the patient and control groups. There was a slight but significant association between DRD3 receptor gene, heroin and cocaine addiction, which was found to be consistent with some of the literature.