Forensic considerations on STR databases in Argentina

Abstract

A genetic comparison study was conducted between populations from different regions of Argentina in order to determine if a pooled population STR database could be used for general forensic purposes. Samples were from urban populations of six geographically distant provinces of Argentina (Tucumán, San Luis, La Pampa, Buenos Aires, Neuquén and Santa Cruz), and two Native American populations from the North and Northwest region of the country (Tobas and Collas). Fifteen autosomal markers were analyzed. Exact tests did not show deviations from Hardy–Weinberg equilibrium. Low Fst values were observed for population pairwise comparisons. However, significant differences were found when comparing Buenos Aires with Neuquén, San Luis and Santa Cruz, and Neuquen with La Pampa. Concerning Native American populations, Fst P-values were statistically significant when comparing Tobas and Collas with all urban populations and between them. Single locus comparisons showed significant differences when comparing Neuquén and Buenos Aires at D5S818, FGA and Penta E loci, between Buenos Aires and Santa Cruz at PENTA E locus, and between Neuquen and Santa Cruz at PENTA E locus. However, no significant differences were found between the urban samples from San Luis, Santa Cruz, Tucumán and La Pampa. When comparing urban populations with Amerindians and European populations, significant P-values were observed at 12–15 loci. The four non-differentiated urban populations were pooled and P-values showed no deviation for Hardy–Weinberg equilibrium. A combined matching probability of 2.0×10−18 and an a priori chance of exclusion of 0.9999995 were obtained. These results suggest that it would be possible to use a combined database for Tucumán, San Luis, La Pampa and Santa Cruz, as no significant differences were found between them. Caution should be taken concerning small isolates where Native American component could be much more relevant. When comparing Argentina urban population with two Iberian samples, some significant differences were found. Therefore, an Iberian database might not adequately represent the Argentinean genetic makeup.