TP53 polymorphisms and haplotypes in South Amerindians and neo-Brazilians

Abstract

To evaluate the genetic diversity of Brazilian populations and contribute to the knowledge of their evolutionary history this study investigated three TP53 polymorphisms (BstUI and MspI RFLPs in exon 4 and intron 6, respectively, and a 16bp duplication in intron 3). The populations studied were: 114 Amerindians from five Brazilian Indian tribes (Gavião, Surui, Zoró, Wai-Wai and Xavante), 95 Euro-Brazilians and 70 Afro-Brazilians. The polymorphisms were all analysed using PCR amplifications. Gene frequencies and haplotype prevalences were calculated using the ARLEQUIN software. The genetic affinities of these groups with other world populations were estimated by the D_A distance and neighbour joining method, using the NJBAFD computer program. Neo-Brazilians (immigrants from Europe and Africa) generally presented more variability than Amerindians, Afro-Brazilians being the most variable population. Among Amerindians, Gavião is the only group polymorphic for the three markers. Wai-Wai showed variability in BstUI and MspI RFLPs, while the other tribes were monomorphic for the 16bp A1 and MspI A2 alleles. A rare haplotype (1-2-1) was verified among the Wai-Wai. This haplotype was previously described in a Chinese sample only, but with low frequency. Therefore, either this combination was lost in the other tribes by genetic drift, recombination, or other factor, or it occurs in the Wai-Wai and Chinese by independent events. The Gavião also presented a haplotype (2-1-1) not observed in the other Amerindians; but since it is present in Euro- and Afro-Brazilians, its occurrence there is probably due to interethnic admixture. The relationships of several world populations obtained using TP53 indicates that this marker is very efficient in clustering populations of the same ethnic group.