Polymorphism of dopamine D2 and D4 receptor genes and Slavic-surnamed alcoholic patients.

The association between alcoholism and the Taq1 "A" and "B" polymorphic alleles at the DRD2 gene and 48-bp tandem repeat in exon 3 of dopamine D4 receptor (DRD4) gene in 42 unrelated Slavic-surnamed patients and 76 normal controls was examined. The frequency of the A1 allele was higher in alcoholic patients and in alcoholic patients with a family history of alcoholism than in controls (χ²= 3.45, p < 0.001 and χ²)= 3.97, p < 0.001, respectively). Moreover, the frequency of the A1 allele was higher in alcoholics with a family history of alcoholism than in alcoholics without a family history (χ²= 3.33, p < 0.001).The results of association analysis for both the Taq1 "B" and DRD4 alleles were negative for alcoholics in general, subgroups of alcoholics and normal controls. However, the 7-repeat allele (DRD47R) of DRD4 gene occurred at significantly higher frequency in alcoholics with a family history of alcoholism compared with those without a family history (χ²= 3.42, p < 0.01).The results indicate that the A1 allele of the DRD2 gene is associated with susceptibility to alcoholism in general.The A1 allele, as well as the DRD47R allele, is significantly prevalent among alcoholics with a family history, in comparison with alcoholics without a family history, reflecting different roles of genetic factors in development of alcoholism.