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 (SL C6A3) 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 varian ts, while the SLC6A3 locus was monomorphic for the 10 repeat allele in Sout h American Indians. Genetic distances and the corresponding neighbor-joinin g tree indicated a geographic dichotomy beta een North + Central American a nd South American natives, with the exception of the Wai Wai, who live nort h of the Amazon river and are grouped in the northern cluster. G(ST) estima tes 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 othe r systems, as well as with the history and biodemographical data of South A merican Indians. (C) 2000 Wiley-Liss, Inc.