Possible interaction between MAOA and DRD2 genes associated with antisocial alcoholism among Han Chinese men in Taiwan.

Both monoamine oxidase A (MAOA) and dopamine D(2) receptor (DRD2) genes have been considered as candidate genes for antisocial personality disorder with alcoholism (Antisocial ALC) [Parsian, A., 1999. Sequence analysis of exon 8 of MAO-A gene in alcoholics with antisocial personality and normal controls. Genomics. 45, 290-295.; Samochowiec, J., Lesch, K.P., Rottmann, M., Smolka, M., Syagailo, Y.V., Okladnova, O., Rommelspacher, H., Winterer, G., Schmidt, L.G., Sander, T., 1999. Association of a regulatory polymorphism in the promoter region of the monoamine oxidase A gene with antisocial alcoholism. Psychiatry. Res. 86, 67-72.; Schmidt, L.vG., Sander, T., Kuhn, S., Smolka, M., Rommelspacher, H., Samochowiec, J., Lesch, K.P., 2000. Different allele distribution of a regulatory MAO-A gene promotor polymorphism in antisocial and anxious-depressive alcoholics. J. Neural .Transm. 107, 681-689.]. However, the association between alcoholism and MAOA or DRD2 gene has not been universally accepted [Lee, J.F., Lu, R.B., Ko, H.C., Chang, F.M., Yin, S.J., Pakstis, A.J., Kidd, K.K., 1999. No association between DRD(2) locus and alcoholism after controlling the ADH and ALDH genotypes in Chinese Han population. Alcohol. Clin. Exp. Res. 23, 592-599.; Lu, R.B., Lin, W.W., Lee, J.F., Ko, H.C., Shih, J.C., 2003. Neither antisocial personality disorder nor antisocial alcoholism association with MAOA gene among Han Chinese males in Taiwan. Alcohol. Clin. Exp. Res. 27, 889-893.]. Since dopamine is metabolized to 3,4-dihydroxyphenyl-acetaldehyde (DOPAL) via monoamine oxidase (MAO) [Westerink, B.H., de Vries, J.B., 1985. On the origin of dopamine and its metabolite in predominantly noradrenergic innervated brain areas. Brain. Res. 330, 164-166.], the interaction between MAOA and DRD2 genes might be related to Antisocial ALC. The present study aimed to determine whether Antisocial ALC might be associated with the possible interactions of DRD2 gene with MAOA gene. Of the 231 Han Chinese subjects who were recruited for the study, 73 participants were diagnosed with Antisocial ALC and 158 subjects were diagnosed with antisocial personality disorder without alcoholism (Antisocial Non-ALC). The DRD2 TaqI A and MAOA-uVNTR (variable number of tandem repeat located upstream) polymorphisms were not found to be associated with Antisocial ALC. However, an association between DRD2 TaqI A polymorphisms and Antisocial ALC was shown only after stratification for the MAOA-uVNTR 4-repeat polymorphism. Additionally, after multiple logistic regressions, we found that, under stratification of MAOA-uVNTR 4-repeat polymorphism and in comparison with the DRD2 A1/A1 genotype as a reference group, the DRD2 A1/A2 genotype has a possible protective effect against alcoholism in individuals with antisocial personality disorder (ASPD). We concluded that the possible interactions between MAOA-uVNTR polymorphism and DRD2 TaqI A polymorphism might be related to Antisocial ALC among Han Chinese men in Taiwan.