We observed that both DRD1 and DRD2 polymorphisms were associated with opiate and cocaine dependence (P < 0.05) in Caucasian subjects, but not African-American individuals.
Using the transmission disequilibrium test, the present study examined linkage disequilibrium of alcohol and drug (opioid and/or cocaine) dependence with three DRD2 polymorphic systems: (a) TaqI A, (b) TaqI D, and (c) the functional -141CIns/Del promoter systems.
We genotyped the Int8 and 3'UTR variable number of tandem repeats of the dopamine transporter gene (DAT1/SLC6A3), the TaqIA (rs1800497) and TaqIB (rs1079597) SNP polymorphisms within the dopamine receptor D2 gene and the 19-bp insertion/deletion and c.444G>A (rs1108580) polymorphisms of the dopamine β-hydroxylase gene (DBH) in a Spanish sample of 169 patients with cocaine addiction and 169 sex-matched controls.
The data showing a strong association of the minor alleles (A1 and B1) of the DRD2 with cocaine dependence suggest that a gene, located on the q22-q23 region of chromosome 11, confers susceptibility to this drug disorder.
We genotyped the Int8 and 3'UTR variable number of tandem repeats of the dopamine transporter gene (DAT1/SLC6A3), the TaqIA (rs1800497) and TaqIB (rs1079597) SNP polymorphisms within the dopamine receptor D2 gene and the 19-bp insertion/deletion and c.444G>A (rs1108580) polymorphisms of the dopamine β-hydroxylase gene (DBH) in a Spanish sample of 169 patients with cocaine addiction and 169 sex-matched controls.
Several studies have looked for a link between cocaine addiction and the genes of the dopaminergic system: the genes DRD2, COMT, SLC6A3 (coding for the dopamine transporter DAT) and DBH (coding for the dopamine beta hydroxylase) but unfortunately very few well established results.