TP53 polymorphisms and haplotypes in South Amerindians and neo-Brazilians

To evaluate the genetic diversity of Brazilian populations and contribute t o the knowledge of their evolutionary history this study investigated three TP53 polymorphisms (BstUI and MspI RFLPs in exon 4 and intron 6, respectiv ely, and a 16 bp duplication in intron 3). The populations studied were: 11 4 Amerindians from five Brazilian Indian tribes (Gaviao, Surui, Zoro, Wai-W ai and Xavante), 95 Euro-Brazilians and 70 Afro-Brazilians. The polymorphis ms were all analysed using PCR amplifications. Gene frequencies and haploty pe prevalences were calculated using the ARLEQUIN software. The genetic aff inities of these groups with other world populations were estimated by the DA distance and neighbour joining method, using the NJBAFD computer program . Neo-Brazilians (immigrants from Europe and Africa) generally presented mo re variability than Amerindians, Afro-Brazilians being the most variable po pulation. Among Amerindians, Gaviao is the only group polymorphic for the t hree markers. Wai-Wai showed variability in BstUI and MspI RFLPs, while the other tribes were monomorphic for the 16 bp A1 and MspI A2 alleles. A rare haplotype (1-2-1) was verified among the Wai-Wai. This haplotype was previ ously described in a Chinese sample only, but with low frequency. Therefore , either this combination was lost in the other tribes by genetic drift, re combination, or other factor, or it occurs in the Wai-Wai and Chinese by in dependent events. The Gaviao also presented a haplotype (2-1-1) not observe d in the other Amerindians; but since it is present in Euro- and Afro-Brazi lians, its occurrence there is probably due to interethnic admixture. The r elationships of several world populations obtained using TP53 indicates tha t this marker is very efficient in clustering populations of the same ethni c group.