T Allele of the DRD2 Taq1 A Gene Polymorphism Increases the Predisposition to Drug Addiction in Indonesian Population

Abstract

Dopamine plays an important role in mediating the rewarding properties in the abuse of drugs. The Taq1A polymorphism is a commonly studied DRD2 gene variant whereby carriers of the low-function T allele (T/T or T/C genotypes) show reduced brain dopamine function. Therefore, individuals who have the DRD2 Taq1A polymorphism will experience higher levels of drug addiction because the T allele is associated with a reduced number of dopamine binding sites in the brain. A study of this gene has been conducted in some areas, but there is no research for the population of Indonesia. This study will focus on the frequency of the DRD2 Taq1A gene polymorphism in the population of Indonesia and define its association with drug addiction. This is a cross sectional study in which 182 subjects were divided into 91 drugaddicted patients and 91 non-drug-addicted control subjects. The genotype analysis was carried out by a modified allele-specific Polymerase Chain Reaction (PCR) method. The frequency of the T/T and C/T was significantly higher in the addicted than control subjects. They are 6.6% and 63.7% compared to 0% and 3.3%. Likewise, the T allele is more frequent in the addicted equal to 38%, compared to only 2% in the control subjects. The frequency of the T allele between the addicted and control subjects shows a significant difference (p-value < 0.0001; 95% CI), with the addicted being at a higher risk of having the T allele (OR = 37.3; 95% CI [11.46-121.29]). There is a significant difference in the frequency of the DRD2 Taq1A gene polymorphism between addicted patients and control subjects. Thus, there is an association between this gene polymorphism and the development of drug addiction with T allele increases the predisposition to addiction.