Genetic admixture patterns in Argentinian Patagonia.

As in other Latin American populations, Argentinians are the result of the admixture amongst different continental groups, mainly from America and Europe, and to a lesser extent from Sub-Saharan Africa. However, it is known that the admixture processes did not occur homogeneously throughout the country. Therefore, considering the importance for anthropological, medical and forensic researches, this study aimed to investigate the population genetic structure of the Argentinian Patagonia, through the analysis of 46 ancestry informative markers, in 433 individuals from five different localities.

Population data of 15 autosomal STR markers from Afro-Bolivians of Nor Yungas Province (Bolivia).

Allele frequencies and forensic parameters for 15 autosomal loci included in the AmpFlSTR® Identifiler kit were estimated in a sample of 57 unrelated Afro-descendants from Nor Yungas (Bolivia). Buccal swabs samples were obtained from voluntary donors, after consent was given. All loci were in Hardy-Weinberg equilibrium after Bonferroni correction.

Paleogenetical study of pre-Columbian samples from Pampa Grande (Salta, Argentina).

Ancient DNA recovered from 21 individuals excavated from burial sites in the Pampa Grande (PG) region (Salta province) of North-Western Argentina (NWA) was analyzed using various genetic markers (mitochondrial DNA, autosomal STRs, and Y chromosomal STRs). The results were compared to ancient and modern DNA from various populations in the Andean and North Argentinean regions, with the aim of establishing their relationships with PG. The mitochondrial haplogroup frequencies described (11% A, 47% B, and 42% D) presented values comparable to those found for the ancient Andean populations from Peru and San Pedro de Atacama.

Brief communication: Restricted geographic distribution for Y-Q* paragroup in South America.

We analyzed 21 paragroup Q* Y chromosomes from South American aboriginal and urban populations. Our aims were to evaluate the phylogenetic status, geographic distribution, and genetic diversity in these groups of chromosomes and compare the degree of genetic variation in relation to Q1a3a haplotypes. All Q* chromosomes from our series and five samples from North American Q* presented the derivate state for M346, that is present upstream to M3, and determined Q1a3* paragroup.

HLA-DRB1 alleles in four Amerindian populations from Argentina and Paraguay.

The major histocompatibility complex (MHC) is one of the biological systems of major polymorphisms. The study of HLA class II variability has allowed the identification of several alleles that are characteristic to Amerindian populations, and it is an excellent tool to define the relations and biological affinities among them. In this work, we analyzed the allelic distribution of the HLA-DRB1 class II locus in four Amerindian populations: Mapuche (n = 34) and Tehuelche (n = 23) from the Patagonian region of Argentina, and Wichi SV (n = 24) and Lengua (n = 17) from the Argentinean and Paraguayan Chaco regions, respectively.

How many populations set foot through the Patagonian door? Genetic composition of the current population of Bahía Blanca (Argentina) based on data from 19 Alu polymorphisms.

The city of Bahía Blanca occupies a strategic place in Argentina south of the Pampean region in the north-east corner of the Patagonia. Since 1828, this city has been the historical and political border between Amerindian lands in the south, and the lands of European colonists. Nowadays, Bahía Blanca is an urban population mainly composed by descendents of immigrants from Spain and other European countries with apparently low admixture with Amerindians.

Allele and genotype frequencies of metabolic genes in Native Americans from Argentina and Paraguay.

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.

[Gene mixture in a population sample from Buenos Aires City].

The aim of this study is to estimate the gene admixture in the population of Buenos Aires City from samples of blood donors, which come from a public health centre (Hospital de Clínicas). These studies were performed on 218 unrelated people, who donated blood during the year 2002. Eight erythrocyte genetic systems and GM/KM allotypes were analysed.

T-cell and chemokine receptor variation in south Amerindian populations.

The immune response of relatively small, endogamous populations is of special interest, because they may differ from those of large, ethnically diverse, urban groups. As a contribution to this area of investigation, we tested 99 individuals from two Brazilian native populations for two T-cell receptor gene segments (TCRBV3S1 and TCRBV18) and 241 subjects from eight tribes of this ethnic group in relation to the chemokine receptor CCR5delta32 allele. Differences in TCRBV3S1 and TCRBV18 prevalences of the Amerindians in relation to European- and African-derived individuals were not marked.

Intra- and intercontinental molecular variability of an Alu insertion in the 3' untranslated region of the LDLR gene.

One-hundred three individuals from two Mongolian, two Siberian, and ten native American populations were studied in relation to a 340-bp sequence from an Alu insertion located in the 3' untranslated region of the LDLR gene. Seven haplotypes have been determined, and haplotype B1 was the most common, accounting for about half the sequences found. In general, diversity values are quite high, about 2.

African ancestry of the population of Buenos Aires.

The population of Argentina today does not have a "visible" black African component. However, censuses conducted during most of the 19th century registered up to 30% of individuals of African origin living in Buenos Aires city. What has happened to this African influence? Have all individuals of African origin died, as lay people believe? Or is it possible that admixture with the European immigrants made the African influence "invisible?" We investigated the African contribution to the genetic pool of the population of Buenos Aires, Argentina, typing 12 unlinked autosomal DNA markers in a sample of 90 individuals.

New genetic data on Amerindians from the Paraguayan Chaco.

New data on 17 blood group and protein genetic systems obtained among the Ayoreo and Lengua Indians of Paraguay are presented. They include the first report on the red cell band-3 protein investigated among South American Indians. This information was integrated with previous results available for these two and four other groups.

Genetic relationships between Amerindian populations of Argentina.

A total of 495 individuals from five different Argentinian tribes was examined for variation in 23 blood group and protein genetic systems, and the results were integrated with previous data on some of these systems. These tribes generally present RH * R1, PGM1 * 1, and ACP * A frequencies lower and RH * R2, ESD * 1, and GLO * 1 prevalences higher than those observed in other South American Indian groups. Earlier studies with mitochondrial DNA showed that haplogroup A was present in low frequencies in these tribes, but haplogroup B showed a high prevalence among the Mataco.

High heterogeneity of apolipoprotein E gene frequencies in South American Indians.

The apolipoprotein E (APOE) polymorphism was investigated in 186 individuals from six South American Indian tribes, and the results integrated with those previously presented for this ethnic group. The three APOE alleles commonly reported in other populations were also observed in South Amerindians with a highly heterogeneous distribution. As in other populations, APOE*3 was the most common allele (51-98%) followed by APOE*4 (2-47%).

Apolipoprotein B signal peptide polymorphism distribution among south Amerindian populations.

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.

HTLV type I and HTLV type II infection among Indians and natives from Argentina.

Endemic foci for HTLV-II infection have been identified in several Amerindian populations. To determine HTLV-I and/or HTLV-II infection among Amerindians living in Argentina we studied 454 sera or plasmas from Indians and natives from different areas of our country. All samples were tested by the particle agglutination technique, and positive reactions were confirmed by the immunofluorescence assay (IFA).

Founder mitochondrial haplotypes in Amerindian populations.

It had been proposed that the colonization of the New World took place by three successive migrations from northeastern Asia. The first one gave rise to Amerindians (Paleo-Indians), the second and third ones to Nadene and Aleut-Eskimo, respectively. Variation in mtDNA has been used to infer the demographic structure of the Amerindian ancestors.

Sexual dimorphism in schoolchildren of the Villa IAPI neighborhood (Quilmes, Buenos Aires, Argentina).

Villa IAPI is a poor neighborhood of about 5,000 inhabitants in the overpopulated conurbano bonaerense at the outskirts of the city of Buenos Aires. Most of the adult male residents are construction workers; the rest are temporary workers, underemployed, or unemployed. The inhabitants of Villa IAPI suffer the effects of many adverse socio-economic conditions, including poor nutrition, deficient sanitation, and inadequate medical care.

[Growth in school children of Villa IAPI (Quilmes, Buenos Aires, Argentina)].

Growth in schoolchildren of Villa IAPI--a poor neighborhood placed near Buenos Aires (Argentina)--were cross-sectionally studied. Six hundred and forty five--291 males and 354 females--children from six to twelve years old were weighed (W), and the standing (StH) and sitting (SiH) heights, the head (HC) and the arm (AC) circumferences, and the triceps (TS) an the subscapular (SS) skinfolds were measured. The muscular braquial circumference (MC), and the length of the inferior segment of the body (IS) were also calculated.

Genetic variation among the Mapuche Indians from the Patagonian region of Argentina: mitochondrial DNA sequence variation and allele frequencies of several nuclear genes.

DNA samples from 60 Mapuche Indians, representing 39 maternal lineages, were genetically characterized for (1) nucleotide sequences of the mtDNA control region; (2) presence or absence of a nine base duplication in mtDNA region V; (3) HLA loci DRB1 and DQA1; (4) variation at three nuclear genes with short tandem repeats; and (5) variation at the polymorphic marker D2S44. The genetic profile of the Mapuche population was compared to other Amerinds and to worldwide populations. Two highly polymorphic portions of the mtDNA control region, comprising 650 nucleotides, were amplified by the polymerase chain reaction (PCR) and directly sequenced.