RESUMO
N-acetyltransferase 2 (NAT2) is responsible for metabolizing xenobiotics; NAT2 polymorphisms lead to three phenotypes: rapid, intermediate and slow acetylators. We aimed to investigate NAT2 diversity in Native Americans. NAT2 exon 2 was sequenced for 286 individuals from 21 populations (Native American and American Mestizos). Excluding the basal/rapid haplotype NAT2*4, the most frequent haplotypes are NAT2*5B (35.95%) in hunter-gatherers and NAT2*7B (20.61%) and NAT2*5B (19.08%) in agriculturalists that were related to the slow phenotype. A new haplotype was identified in two Amerindians. Data from the ~44 kb region surrounding NAT2 in 819 individuals from Africa, East-Asia, Europe and America were used in additional analyses. No significant differences in the acetylator NAT2 haplotype and phenotype distributions were found between Native American populations practicing farming and/or herding and those practicing hunting and gathering, probably because of the absence or weakness of selection pressures and presence of demographic and random processes preventing detection of any selection signal.
Assuntos
Indígena Americano ou Nativo do Alasca/genética , Arilamina N-Acetiltransferase/genética , Evolução Molecular , Variação Genética , Acetilação , Agricultura , América , Animais , Arilamina N-Acetiltransferase/metabolismo , Dieta/etnologia , Comportamento Alimentar/etnologia , Frequência do Gene , Haplótipos , Humanos , Cinética , Fenótipo , Comportamento Predatório , Xenobióticos/metabolismoRESUMO
Interethnic differences in the allele frequencies of CYP2D6, NAT2, GSTM1 and GSTT1 deletions have been documented for Caucasians, Asians, and Africans population. On the other hand, data on Amerindians are scanty and limited to a few populations from southern areas of South America. In this report we analyze the frequencies of 11 allele variants of CYP2D6 and 4 allele variants of NAT2 genes, and the frequency of GSTM1 and GSTT1 homozygous deleted genotypes in a sample of 90 donors representing 8 Native American populations from Argentina and Paraguay, identified as Amerindians on the basis of their geographic location, genealogical data, mitochondrial- and Y-chromosome DNA markers. For CYP2D6, 88.6% of the total allele frequency corresponded to *1, *2, *4 and *10 variants. Average frequencies for NAT2 *4, *5, *6 and *7 alleles were 51.2%, 25%, 6.1%, and 20.1%, respectively. GSTM1 deletion ranged from 20% to 66%, while GSTT1 deletion was present in four populations in less than 50%. We assume that CYP2D6 *2, *4, *10, *14; NAT2 *5, *7 alleles and GSTM1 and GSTT1 *0/*0 genotypes are founder variants brought to America by the first Asian settlers.
Assuntos
Arilamina N-Acetiltransferase/genética , Citocromo P-450 CYP2D6/genética , Frequência do Gene/genética , Glutationa Transferase/genética , Indígenas Norte-Americanos/genética , Alelos , Argentina/etnologia , Sistema Enzimático do Citocromo P-450 , Deleção de Genes , Genótipo , Humanos , Paraguai/etnologia , Polimorfismo GenéticoRESUMO
We investigated the incidence of the Region V mitochondrial DNA 9-base-pair (bp) deletion from human remains recovered from several archaeological sites and contexts throughout Argentina. Of the 34 samples analyzed, 24 yielded DNA extractions that gave clear amplification results. All of the individuals carried two repeats of the 9 bp, one of which has been shown to be deleted in some individuals of Asian origin and defines mitochondrial lineage B. Although most of the modern Amerindian groups in the region exhibit the deletion in high frequencies, the absence of the 9-bp deletion among ancient populations of South America seems to be the rule rather than the exception, as was reported by several studies involving extinct populations. The evidence gathered until now suggests that the earliest settlers of this region of South America did not carry mitochondrial lineage B.
Assuntos
Pareamento de Bases/genética , Deleção Cromossômica , DNA Mitocondrial/história , Emigração e Imigração/história , Frequência do Gene/genética , Paleodontologia , Argentina , DNA Mitocondrial/genética , História Antiga , Humanos , Incidência , Reação em Cadeia da PolimeraseRESUMO
Mitochondrial DNA from 141 individuals was typed for diagnostic restriction sites and the 9-bp region V deletion to examine the distribution of the founding mtDNA lineage haplotypes in three Amerindian populations (Mataco, Toba, and Pilagá) who currently inhabit the Argentinian part of the Gran Chaco. All four lineages were identified in the three tribes and four population samples studied. Disregarding ethnic or geographic origin, haplogroups B and D exhibit high incidence among the Gran Chaco inhabitants, whereas haplogroups A and C are present in a lower frequency. Three individuals possess none of the characteristic markers and, therefore, could not be assigned to one of those lineages. A neighbor-joining representation of F(ST) distances reflects the current geographic location of the populations, and this also corresponds to their historic distribution. After separating South America into four major regions (Tropical Forest, Andes, Gran Chaco, and Patagonia-Tierra del Fuego), the Gran Chaco populations present the highest average intragroup variability (Hs = 0.64) as well as the lowest intergroup diversity (G(')(ST) = 0.06). These findings suggest high levels of gene flow among the Chaco tribes, as well as with neighbor populations from outside the region.
Assuntos
DNA Mitocondrial/genética , Emigração e Imigração , Genética Populacional , Indígenas Norte-Americanos , Haplótipos , Humanos , Dinâmica Populacional , América do SulRESUMO
On the basis of erythrocyte and serum protein polymorphisms, we investigated the level of genetic differentiation among 3 Argentinian native populations sharing ethnic and morphological characteristics but inhabiting different altitudes in the Andes. Of the 15 loci studied, 8 are monomorphic. Phenotype distribution of the polymorphic systems are in agreement with Hardy-Weinberg equilibrium, except for malic enzyme (MOD), where a silent allele was found. The 2 highland populations exhibit a close genetic similarity, probably as a result of intense gene flow. The lowland population shows reduced genetic diversity, which suggests the influence of stochastic phenomena such as the founder effect.
Assuntos
Altitude , Indígenas Sul-Americanos/genética , Repetições Minissatélites/genética , Polimorfismo Genético/genética , População Branca/genética , Alelos , Argentina , Distribuição de Qui-Quadrado , Feminino , Frequência do Gene , Genética Populacional , Humanos , Masculino , Estudos de AmostragemRESUMO
We report the distribution of the APOB signal peptide polymorphism in 5 native populations of South America: 2 samples of Mataco and 1 sample each of Pilagá and Toba from the Argentinian Chaco and 1 sample of Ache from the Paraguay forest. A randomly selected subsample of a previously studied sample from the Cayapa of Ecuador (Scacchi et al. 1997) was reanalyzed to investigate probable differences attributable to sampling, laboratory techniques, or interobserver error. The polymorphism observed in the signal peptide region of the APOB gene among native populations of South America exhibits the same range of variation found among geographic continental populations, confirming the high genetic heterogeneity of South Amerindians. Extremes in the allele prevalences were found among the Mataco and Ache, populations not far apart geographically. The small differences in genotype and allele frequencies between the subsample of the Cayapa analyzed here and the original Cayapa sample and between the 2 Mataco samples were not statistically significant and most likely were due to sampling error.
Assuntos
Apolipoproteínas B/genética , Variação Genética/genética , Indígenas Sul-Americanos/genética , Polimorfismo Genético/genética , Sinais Direcionadores de Proteínas/genética , Alelos , Argentina , Viés , Frequência do Gene/genética , Heterogeneidade Genética , Genótipo , Humanos , ParaguaiRESUMO
Electrophoretic polymorphism at loci coding for blood red cells and plasma proteins was analysed in three native populations of South America: Mataco and Macá (from the Gran Chaco), and Guayaki (from the Paraguayan forest). Mean heterozygosity per locus varied from 0.024 and 0.073, the Macá being the most polymorphic population, probably reflecting admixture with the caucasoid population of Asuncion city. Although the external phenotype, blood group frequencies and ethno-linguistic affiliation of the Guayaki clearly differ from those of the Chaco tribes, Nei's genetic distances were very low and almost equidistant among the three populations. Heterogeneity of F(ST) values among polymorphic loci would suggest the action of natural selection.
Assuntos
Indígenas Sul-Americanos/genética , Polimorfismo Genético , Proteínas/genética , HumanosRESUMO
The biological affinities among 17 South American aboriginal populations are examined by means of a multivariate analysis of their dermatoglyphic finger patterns. Different analytical methods [cluster analysis, nonmetric multidimensional scaling, and multiresponse permutation procedure (based on distances derived from principal components analysis)] reveal interpopulation relationships consistent with Loukotka's language classification. The paleo-American tribes from the Gran Chaco and Brazil share a high incidence of whorls as a distinctive feature. The Andean and tropical forest groups, which present a greater prevalence of arches and ulnar loops, appear to be closely related to each other, suggesting a more recent common origin and/or substantial gene flow between them.
Assuntos
Dermatoglifia , Indígenas Sul-Americanos/genética , Argentina , Brasil , Análise por Conglomerados , Feminino , Humanos , Masculino , Análise Multivariada , Vigilância da População , Estudos de Amostragem , América do SulRESUMO
Digital and palmar dermatoglyphics are reported for 94 Araucanian Indians from the Argentinian Patagonia. All the traits analyzed present values within the range of variation found in South Amerindians. The principal finding is the different behavior observed for the digital and palmar traits of the individuals of the tribe. Although finger variables show high sexual and bimanual variation (especially in males), palmar traits exhibit extreme homogeneity. Multiple discriminant analyses from palmar data and finger ridge counts separately were carried out with three other Argentinian Indian populations from the Gran Chaco. The results indicate high discrimination between the populations in both palmar variables and finger ridge counts. However, although the nature of interpopulation relationships obtained from palmar data conforms to the ethnohistorical and geographic patterns, no clear picture emerges when the finger ridge counts are used.
Assuntos
Dermatoglifia , Genética Populacional , Indígenas Sul-Americanos , Argentina , Feminino , Humanos , Masculino , Análise MultivariadaRESUMO
The present report deals with digital and palmar dermatoglyphics of a sample of 98 Chorote indians, collected in the north of Argentina, in the Gran Chaco region. Bimanual dimorphism was observed in males and females, both in finger and in palmar variables. Significant differences between sexes appear only in digital ridge counts and in the combined incidence of the four pattern types the Chorote, in general, show low sexual dimorphism. Univariate comparisons carried out with other tribes of the Gran Chaco (Chiriguano, Pilagá, Mataco, and Toba) indicate statistically significant differences between these and the Chorote, both in males and females. The greatest differences were found in relation to the Mataco, who belong to the same linguistic family as the Chorote. Probable explanations for these differences are proposed.