MtDNA ancestry of Rio de Janeiro population, Brazil.

Polymorphism studies concerning HVI and HVII regions of mitochondrial DNA (mtDNA) have improved the understanding of the admixture genetic process related to the occupation of the continents by human population groups. We have analyzed the mtDNA lineages of 190 healthy and maternally unrelated individuals born in the metropolitan region of the Rio de Janeiro city, the capital of the State of Rio de Janeiro, southeastern Brazil. The data showing that 57.9, 25.3 and 16.8 % of the matrilineages found in Rio de Janeiro come from African, Amerindian and European population groups. They are, respectively, in close agreement with historical records which indicate that the admixture population of Brazil is the resulting of interethnic asymmetry crosses between individuals from those population groups. The high proportion of African mtDNA lineages in the population of Rio de Janeiro is in accordance with studies related to other Brazilian states.

Analysis of 12 X-STRs loci in a population from southeastern Brazil.

Short tandem repeat (STR) markers on the X chromosome have a high potential for solving complex kinship analysis and individual identification cases. To achieve such purposes, allele and haplotype frequencies for the specific population are necessary. Nonetheless, such frequencies are not always available. Therefore, we obtained haplotypes from 520 unrelated males from four different geographic regions of Espírito Santo - Brazil, using the Investigator Argus X-12 kit. Forensic parameters for linked groups of four X-STR loci are reported. Genetic distance analyzes suggest that ES population is genetically closer to the Italian population and farther from the Mexican one, among the populations analyzed in this study.

The mitogenomic phylogeny of the Elasmobranchii (Chondrichthyes).

Here we present a mitogenomic perspective on the evolution of sharks and rays, being a first glance on the complete mitochondrial history of such an old and diversified group of vertebrates. The Elasmobranchii is a diverse subclass of Chondrichthyes, or cartilaginous fish, with about 1200 species of ocean- and freshwater-dwelling fishes spread all over the world's seas, including some of the ocean's largest fishes. The group dates back about 400 million years near the Devonian-Silurian boundary, being nowadays represented by several derivative lineages, mainly related to Mesozoic forms. Although considered of ecological, commercial and conservation importance, the phylogeny of this old group is poorly studied and still under debate. Here we apply a molecular systematic approach on 82 complete mitochondrial genomes to investigate the phylogeny of the Elasmobranchii. By using maximum likelihood (ML) and Bayesian analyses, we found a clear separation within the shark clade between the Galeomorphii and the Squalomorphii, as well as sister taxa relationships between the Carcharhiniformes and the Lamniformes. Moreover, we found that Pristoidei clusters within the Rhinobatoidei, having been recovered as the sister taxon of the Rhinobatos genus in a clade which also includes the basal Zapteryx. Our results also reject the Hypnosqualea hypothesis, which proposes that the Batoidea should be placed within the Selachii.

Ser49Gly polymorphism in the ß-adrenergic receptor 1 gene in a population sample from Rio de Janeiro state, Brazil, stratified by self-identified skin color and genetic ancestry.

Cardiovascular diseases (CVD) have the highest worldwide mortality rate of any type of disease. In recent years, genetic research regarding CVD has been conducted using association studies, in which the presence of a genetic polymorphism associated with a specific cell signaling pathway in a lower or in a higher frequency among patients may be interpreted as a possible causal factor. Genetic polymorphisms that occur in the ß-adrenergic receptor 1 (ß-ADR1) can result in significant changes in its function that may result in physiopathologies. Ambiguous categorizations, such as skin color and self-reported ethnicity have been used in pharmacogenetic studies as phenotypic proxies for ancestry; however, admixed populations present a particular challenge to the effectiveness of this approach. The main objective of the present study was to estimate the diversity and the frequency of the Ser49Gly polymorphism of the ß-ADR1 gene in a sample of 188 male individuals from the population of Rio de Janeiro. The Ser49Gly frequencies were analyzed by two forms of sample stratification: The phenotypic criterion of black or non-black skin color, and African or non-African ancestry, defined using Y-chromosome single nucleotide polymorphisms and autosomal indel markers. These results were used to evaluate whether marker-based ancestry criteria and/or skin color were associated with the frequency of the Ser49Gly polymorphisms in the heterogeneous Rio de Janeiro/Brazilian population. The DNA fragments of interest were amplified by polymerase chain reaction with specific primers for the Ser49Gly marker, and genotyping reactions were performed by restriction with the enzyme Eco0109I. Heterozygosity values ranging from 0.25 to 0.50 and 0.20 to 0.41 were found for the groups stratified by ancestry and skin color, respectively. Using the Hardy-Weinberg equilibrium at the ser49Gly marker, it was found that there was no significant deviation in the genotype distribution of the whole Rio de Janeiro sample or the stratified sample. Analysis of the allelic distribution in the Rio de Janeiro population sample revealed frequencies of 80.30 and 19.70% for the wild-type (Ser49) and mutated (Gly49) alleles, respectively. Significant differences were observed in the allele frequencies of the Ser49Gly marker between the self-defined black and non-black phenotype, and the African and non-African descendant genotype population samples. A significant difference was also observed between blacks and African-descendant individuals, with a lesser degree of genetic differentiation. The results presented in the present study suggest that the Ser49Gly marker has a distribution that is influenced by an ancestral component, due to the increased prevalence of the Gly49 polymorphism in the black and African descendant populations of the Rio de Janeiro state. This evidence, in combination with clinical studies, may contribute to a detailed analysis of the pattern of susceptibility to CVD involved in ß-ADR1 receptor mechanism failure.

Male lineage strata of Brazilian population disclosed by the simultaneous analysis of STRs and SNPs.

Brazil has a large territory divided in five geographical regions harboring highly diverse populations that resulted from different degrees and modes of admixture between Native Americans, Europeans and Africans. In this study, a sample of 605 unrelated males was genotyped for 17 Y-STRs and 46 Y-SNPs aiming a deep characterization of the male gene pool of Rio de Janeiro and its comparison with other Brazilian populations. High values of Y-STR haplotype diversity (0.9999±0.0001) and Y-SNP haplogroup diversity (0.7589±0.0171) were observed. Population comparisons at both haplotype and haplogroup levels showed significant differences between Brazilian South Eastern and Northern populations that can be explained by differences in the proportion of African and Native American Y chromosomes. Statistical significant differences between admixed urban samples from the five regions of Brazil were not previously detected at haplotype level based on smaller size samples from South East, which emphasizes the importance of sample size to detected population stratification for an accurate interpretation of profile matches in kinship and forensic casework. Although not having an intra-population discrimination power as high as the Y-STRs, the Y-SNPs are more powerful to disclose differences in admixed populations. In this study, the combined analysis of these two types of markers proved to be a good strategy to predict population sub-structure, which should be taken into account when delineating forensic database strategies for Y chromosome haplotypes.

Sub-Saharan Africa descendents in Rio de Janeiro (Brazil): population and mutational data for 12 Y-STR loci.

A male sample of 135 African descendents from the Rio de Janeiro population were typed for the 12 Y-chromosome short tandem repeat (STR) loci included in the PowerPlex Y System. A high haplotype diversity was observed (0.9971), with 91% of haplotypes being unique, demonstrating the usefulness and informative power of this Y-STR set in male lineage identification. Samples with shared haplotypes were additionally typed with the Yfiler kit, which includes five extra markers. The haplotype diversity when using the 17-Yfiler loci increased to (0.9998) with 97% unique haplotypes. The same set of Y-STRs was also typed in 135 father/son pairs and three single-step mutations were observed: one at DYS19 and two at DYS385. Genetic distance analysis showed highly significant differences in all pairwise comparisons between this sample of African descendents and the general population from Rio de Janeiro, as well as with Iberian and African samples from Portugal, Mozambique, Angola and Equatorial Guinea. Comparisons with samples from other regions in Brazil showed that heterogeneity does exist, indicating that a Y-haplotype database for the whole country should take into account the population sub-structure. Moreover, a strong European influence was detected, and thus, a Y-chromosome STR profile proves a rather poor indicator for the ethnic origin of an individual in Rio de Janeiro.