Patients with chronic addiction exhibit reduced dopamine D2 receptor (DRD2) availability in the striatum, and the <i>DRD2</i> TaqIA (rs1800497) and C957T (rs6277) genetic polymorphisms have previously been linked to individual differences in striatal dopamine metabolism and clinical risk for alcohol and nicotine dependence.
The A1 allele of the DRD2/ANKK1 Taq1A polymorphism (rs1800497) is associated with reduced striatal D(2/3) receptor binding in healthy individuals (Con) as well as depression and addiction.