RESUMO
We developed a panel of 40 multiplexed short insertion-deletion (indel) polymorphic loci with widespread chromosomal locations and allele frequencies close to 0.50 in the European population. We genotyped these markers in 360 unrelated self-classified White Brazilians and 50 mother-child-probable father trios with proven paternity. The average heterozygosity (gene diversity) per locus was 0.48, and the combined probability of identity (matching probability) for the 40-locus set was 3.48 x 10(-17). The combined power of exclusion of the indel panel was 0.9997. The efficiency of the 40 indel set in the exclusion of falsely accused individuals in paternity casework was equivalent to the CODIS set of 13 microsatellites. The geometric mean of the paternity indices of the 50 mother-child-probable father trios was 17,607. This panel of 40 short indels was found to have excellent performance. Thus, especially because of its simplicity and low cost, and the fact that it is composed of genomic markers that have very low mutation rates, it represents a useful new tool for human paternity testing.
Assuntos
Impressões Digitais de DNA/métodos , Mutação INDEL/genética , Paternidade , Polimorfismo Genético , Loci Gênicos/genética , HumanosRESUMO
We review studies from our laboratories using different molecular tools to characterize the ancestry of Brazilians in reference to their Amerindian, European and African roots. Initially we used uniparental DNA markers to investigate the contribution of distinct Y chromosome and mitochondrial DNA lineages to present-day populations. High levels of genetic admixture and strong directional mating between European males and Amerindian and African females were unraveled. We next analyzed different types of biparental autosomal polymorphisms. Especially useful was a set of 40 insertion-deletion polymorphisms (indels) that when studied worldwide proved exquisitely sensitive in discriminating between Amerindians, Europeans and Sub-Saharan Africans. When applied to the study of Brazilians these markers confirmed extensive genomic admixture, but also demonstrated a strong imprint of the massive European immigration wave in the 19th and 20th centuries. The high individual ancestral variability observed suggests that each Brazilian has a singular proportion of Amerindian, European and African ancestries in his mosaic genome. In Brazil, one cannot predict the color of persons from their genomic ancestry nor the opposite. Brazilians should be assessed on a personal basis, as 190 million human beings, and not as members of color groups.
Assuntos
Variação Genética/genética , Genoma Humano/genética , População Negra/genética , Brasil/etnologia , Cromossomos Humanos Y/genética , DNA Mitocondrial/genética , Feminino , Marcadores Genéticos/genética , Genética Populacional/métodos , Humanos , Indígenas Sul-Americanos/genética , Masculino , Polimorfismo Genético/genética , População Branca/genéticaRESUMO
We review studies from our laboratories using different molecular tools to characterize the ancestry of Brazilians in reference to their Amerindian, European and African roots. Initially we used uniparental DNA markers to investigate the contribution of distinct Y chromosome and mitochondrial DNA lineages to present-day populations. High levels of genetic admixture and strong directional mating between European males and Amerindian and African females were unraveled. We next analyzed different types of biparental autosomal polymorphisms. Especially useful was a set of 40 insertion-deletion polymorphisms (indels) that when studied worldwide proved exquisitely sensitive in discriminating between Amerindians, Europeans and Sub-Saharan Africans. When applied to the study of Brazilians these markers confirmed extensive genomic admixture, but also demonstrated a strong imprint of the massive European immigration wave in the 19th and 20th centuries. The high individual ancestral variability observed suggests that each Brazilian has a singular proportion of Amerindian, European and African ancestries in his mosaic genome. In Brazil, one cannot predict the color of persons from their genomic ancestry nor the opposite. Brazilians should be assessed on a personal basis, as 190 million human beings, and not as members of color groups.
Assuntos
Feminino , Humanos , Masculino , Variação Genética/genética , Genoma Humano/genética , População Negra/genética , Brasil/etnologia , Cromossomos Humanos Y/genética , DNA Mitocondrial/genética , População Branca/genética , Marcadores Genéticos/genética , Genética Populacional/métodos , Indígenas Sul-Americanos/genética , Polimorfismo Genético/genéticaRESUMO
Through microsatellite analysis of 53 monoclonal populations of Trypanosoma cruzi, we found a remarkable degree of genetic polymorphism with no single multilocus genotype being observed more than once. The microsatellite profile proved to be stable during 70 generations of the CL Brener clone in culture. The microsatellite profiling presented also high diagnostic sensitivity since DNA amplifications could be achieved with less than 100 fg DNA, corresponding to half parasite total DNA content. Based on these technical attributes the microsatellite assay turns out to be an important tool for direct typing T. cruzi in biological samples. By using this approach we were able to type T. cruzi in feces of artificially infected bugs and in single cells sorted by FACS. The microsatellites have shown to be excellent markers for T. cruzi phylogenetic reconstruction. We used maximum parsimony based on the minimum number of mutational steps to build an unrooted Wagner network, which confirms previous conclusions based on the analysis of the D7 domain of the LSU rDNA gene that T. cruzi is composed by two major groups. We also obtained evidence that strains belonging to rRNA group 2 are subdivided into two genetically distant clusters, and that one of these clusters is more related to rRNA group (1/2). These results suggest different origins for these strains.