Association of VNTR polymorphisms in the MAOA promoter and DRD4 exon 3 with heroin dependence in male Chinese addicts

Objective. To explore the involvement of variable number tandem repeat (VNTR) polymorphisms in the monoamine oxidase A (MAOA) promoter and exon 3 of the dopamine D4 receptor (DRD4) gene in heroin addiction modulate the vulnerability of individuals to heroin addiction. Methods. Eight hundred and ninety-four male heroin addicts without other psychiatric disorders, were recruited as subjects. Another community 180 males were selected randomly as controls. Results. The geno-distribution of the DRD4 exon 3 VNTR polymorphism in controls was in Hardy–Weinberg equilibrium (HWEχ2=0.925), but the distribution in heroin addicts was not (HWEχ2=28.35). The long-repeat alleles of the DRD4 exon 3 VNTR polymorphism were found more frequently in the heroin addicts (P=0.019). However, the long-repeat alleles of the MAOA promoter VNTR polymorphism were not (P=0.828). No interaction between these two VNTR polymorphisms was found by using multiple logistic regression analysis (P=0.261). Conclusion. The long-repeat allelic var...