The association between dopamine D2 receptor gene

The dopamine D2 receptor (DRD2) gene locus diplays polymorphic genetic markers. Two of them, the TaqI <> and <> Restriction Fragment Length Polymorphisms (RFLP), appear to mark a DRD2 gene variant associated with enhanced liability to severe alcoholism or substance abuse in most studies. Other reports, however, show non-significant trends or fail to repliate the association altogether. Positive findings have thus been criticized as potentially stemming from RFLP frequency differences in distinct Caucasian ethnic groups, a population-genetic phenomenon entirely unrelated to alcoholism per se. Negative results have been viewed, on the other hand, as possibly deriving from a biased selection of non-severe patients in a genetically heterogeneous disorder such as alcoholism. Data from studies published to date will be reviewed, opposing views will be discussed, meta-analyses consistent with contributions by DRD2 gene variants to interindividual differences in vulnerability to alcoholism and polysubstance abuse will be presented. The first single gene identified for its potential contributions to polygenic disorders such as alcoholism and substance abuse, appears to deserve continuing efforts to confirm or refute its role, particularly focused at this stage on functional correlates of A1/B1-marked DRD2 gene variants.