Individual alleles identified by candidate gene analysis have been shown to profoundly influence certain complex behavioral syndromes including vulnerability to alcoholism. The alcohol and aldehyde dehydrogenase polymorphisms, ADH2(2) and ALDH2(2), respectively, are associated with lower vulnerability to alcoholism both in the Orient and also in North America among populations of Taiwanese and Koreans who have immigrated there. Protein structural variants have recently been identified for a series of genes involved in dopamine and serotonin function. Three dopamine receptors exhibit such structural variants, and these include the DRD2 dopamine receptor, which has three relatively rare amino acid substitutions. Structural polymorphisms were detected in five serotonin receptors (5HT1A, 5HT1Db, 5HT2A, 5HT2C, and 5HT7). Association studies between neurotransmitter gene variants and alcoholism are at an earlier stage than with ADH2(2)/ALDH2(2), but results are thus far negative (dopamine DRD4 receptor), equivocal (dopamine DRD2 receptor), or preliminary (tryptophan hydroxylase, 5HT2C and 5HT1Db).