Haplotype and allele frequencies for three genes of the dopaminergic system in South American Indians

Haplotype and allele frequencies for the dopamine D2 receptor gene (DRD2), dopamine D4 receptor gene (DRD4), and dopamine transporter protein gene (SLC6A3) were determined in 135 individuals from five Brazilian Indian tribes, and the results integrated with those previously presented for this ethnic group. DRD2 and DRD4 were highly polymorphic. Haplotypes including TaqI A1 at DRD2, and the seven repeat allele at DRD4 were the most frequent variants, while the SLC6A3 locus was monomorphic for the 10 repeat allele in South American Indians. Genetic distances and the corresponding neighbor‐joining tree indicated a geographic dichotomy between North + Central American and South American natives, with the exception of the Wai Wai, who live north of the Amazon river and are grouped in the northern cluster. GST estimates from these genes vary between 0.05 and 0.11 for North and South America, respectively, indicating a higher degree of differentiation of the latter groups. These results are in accordance with previous genetic data on other systems, as well as with the history and biodemographical data of South American Indians. Am. J. Hum. Biol. 12:638–645, 2000. © 2000 Wiley‐Liss, Inc.