ANKK1 and heroin dependence: According to the data the minor (T) allele containing genotypes (TT+CT) of TaqIA polymorphism (rs1800497) in the ANKK1 gene were overrepresented in patients (6.1%+34%) when compared to the controls (3.2%+27.9%) suggesting a genetic effect of the T allele on heroin dependence risk (p = 0.009).