María Laura Parolín

Heterogeneity in genetic admixture across different regions of argentina

The population of Argentina is the result of the intermixing between several groups, including Indigenous American, European and African populations. Despite the commonly held idea that the population of Argentina is of mostly European origin, multiple studies have shown that this process of admixture had an impact in the entire Argentine population. In the present study we characterized the distribution of Indigenous American, European and African ancestry among individuals from different regions of Argentina and evaluated the level of discrepancy between self-reported grandparental origin and genetic ancestry estimates. A set of 99 autosomal ancestry informative markers (AIMs) was genotyped in a sample of 441 Argentine individuals to estimate genetic ancestry. We used non-parametric tests to evaluate statistical significance. The average ancestry for the Argentine sample overall was 65% European (95%CI: 63–68%), 31% Indigenous American (28–33%) and 4% African (3–4%). We observed statistically significant differences in European ancestry across Argentine regions [Buenos Aires province (BA) 76%, 95%CI: 73–79%; Northeast (NEA) 54%, 95%CI: 49–58%; Northwest (NWA) 33%, 95%CI: 21–41%; South 54%, 95%CI: 49–59%; p<0.0001] as well as between the capital and immediate suburbs of Buenos Aires city compared to more distant suburbs [80% (95%CI: 75–86%) versus 68% (95%CI: 58–77%), p = 0.01]. European ancestry among individuals that declared all grandparents born in Europe was 91% (95%CI: 88–94%) compared to 54% (95%CI: 51–57%) among those with no European grandparents (p<0.001). Our results demonstrate the range of variation in genetic ancestry among Argentine individuals from different regions in the country, highlighting the importance of taking this variation into account in genetic association and admixture mapping studies in this population.

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. In all of these groups, relatively high frequencies of Amerindian HLA-DRB1 alleles were observed (DRB1*0403, DRB1*0407, DRB1*0411, DRB1*0417, DRB1*0802, DRB1*0901, DRB1*1402, DRB1*1406 and DRB1*1602). However, we also detected the presence of non-Amerindian variants in Mapuche (35%) and Tehuelche (22%). We compared our data with those obtained in six indigenous groups of the Argentinean Chaco region and in a sample from Buenos Aires City. The genetic distance dendrogram showed a clear-cut division between the Patagonian and Chaco populations, which formed two different clusters. In spite of their linguistic differences, it can be inferred that the biological affinities observed are in concordance with the geographic distributions and interethnic relations established among the groups studied.

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. D21S11 was the most informative locus, while the least discriminating locus was D3S1358. The combined power of discrimination and the combined probability of exclusion were >0.99999999 and >0.99997, respectively. The multidimensional scaling (MDS) plot generated by Rst matrix supported that Afro-Bolivians of Nor Yungas preserved a stronger African descent compared to other admixed Latin American populations. These results amplified the Bolivian databases of autosomal STR loci and may provide a useful tool for human identification tests and population genetic studies.

Gene Admixture Analysis through Genetic Markers and Genealogical Data in a Sample from the Buenos Aires Metropolitan Area

Several cosmopolitan populations of Argentina have been studied to estimate the European, Amerindian, and African participation in their gene pool. In the city of Buenos Aires, these studies were first made using only blood group markers such as ABO and D factor of Rh system (a revision of these studies was performed by Avena 2003). In addition, Sergio Avena et al. (1999, 216) carried out a comparative analysis between the current data and those available at a historical level using the frequencies of ABO and Rh system, and they were able to find significant differences between the sample of the Hospital de Clinicas of the city of Buenos Aires (register of donors from 1994 to 1995) and the data registered in the city in 1938 and 1949 (see Etcheverry 1949, 167; Avena 2003, 48). In that study, they observed an increase in ABO*O and RH*D alleles due to the important contribution of Amerindian people to the gene pool of the Buenos Aires Metropolitan Area (BAMA) population. Later, we determined ten blood group systems and gm/km immunoglobulins in two samples of the BAMA, and we obtained similar gene admixture values of 14–16 percent and 3.3–4.0 percent with Amerindians and Africans, respectively (Avena et al. 2001, 86; Avena et al. 2006, 115).

DISTRIBUCION ALELICA DEL LOCUS HLA-DRB1 EN POBLACIONES NATIVAS AMERICANAS. EVALUACION DE AFINIDADES EVOLUTIVAS INTRA E INTERCONTINENTALES

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