The A1 allele of the D2 dopamine receptor gene is associated with high dopamine transporter density in detoxified alcoholics.

The A1 allele of TaqI A restriction fragment length polymorphism (RFLP) in the D 2 receptor (DRD 2 ) gene locus has been suggested to be associated with low D 2 receptor density in man. Striatal dopamine transporter (DAT) densities were studied with (123I)2-β-carbometoxy-3β(4-iodophenyl)tropane and single-photon emission tomography in 29 detoxified alcoholics, who were also genotyped for the two alleles of TaqI A RFLP at the DRD2 receptor gene locus. Alcoholics with the A1/A2 genotypes ( n = 10) had statistically significantly higher DAT densities than subjects with the A2/A2 genotypes ( n = 19; 8.0 ± 1.2 (mean ± SD) vs 6.9 ± 1.1, P = 0.035). We suggest that the TaqI A RFLP is in linkage disequilibrium with a gene variant modifying DAT density in alcoholics.