Variation of variable number of tandem repeat sequences in the 3'-untranslated region of primate dopamine transporter genes that affects reporter gene expression.

Genetic polymorphism has been reported in the 3'-untranslated region (3'-UTR) of the human dopamine transporter (DAT) gene and the variable number of tandem repeat (VNTR) polymorphism has been proposed to be associated with normal personal traits or psychoneurological disorders. To assess the variation of this region in nonhuman primates, we amplified the VNTR regions by the polymerase chain reaction in several species of apes and monkeys, and determined their DNA sequences. The 3'-UTR of the chimpanzee DAT gene was also polymorphic and alleles with one or two unit(s) of a 40 bp sequence were found, while all gorillas and orangutans examined had only 2-repeat allele. Cynomolgus macaques and African green monkeys shared 11- or 12-repeat and 5-repeat alleles, respectively. By performing transient transfection assay, we found that most of the VNTR sequences of nonhuman primates exhibited higher activities on reporter gene assay as compared to those of human 9-, 10- and 11-repeat sequences.