The A1 allele of the D-2 dopamine receptor gene is associated with high dopamine transporter density in detoxified alcoholics

The Al allele of TaqI A restriction fragment length polymorphism (RFLP) in the D-2 receptor (DRD2) gene locus has been suggested to be associated with low D-2 receptor density in man. Striatal dopamine transporter (DAT) densi ties were studied with [I-123]2-beta -carbometoxy-3 beta (4-iodophenyl)trop ane 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 t hat the TaqI A RFLP is in linkage disequilibrium with a gene variant modify ing DAT density in alcoholics.