Study of 17 X-STRs in Native American and Mestizo populations of Central America for forensic and population purposes.

In the present work, an extensive analysis of the X-chromosomal pool of Native American and Mestizo groups of Central America (Guatemala, El Salvador, Nicaragua, and Panama) has been carried out. Allele and haplotype frequency databases, as well as other forensic parameters for these populations, are presented. The admixture analysis supports the tri-hybrid composition in terms of ancestry in the Mestizo populations, with a predominant Native American contribution (54-69%), followed by European (19-28%) and African contributions (12-19%). Pairwise FST genetic distances highlight the genetic proximity between the northernmost Central American populations, especially among admixed populations. The unique and complex nature of this area, where populations from different origins intercrossed, as well as the informativity of X-STR data, highpoint the great interest of this genetic study. Furthermore, the X-chromosome databases for Central American populations here provided will be not only useful for forensic and population purposes not only in the target countries but also in the host countries.

A Y-chromosomal survey of Ecuador's multi-ethnic population reveals new insights into the tri-partite population structure and supports an early Holocene age of the rare Native American founder lineage C3-MPB373.

Ecuador is a multiethnic and pluricultural country with a complex history defined by migration and admixture processes. The present study aims to increase our knowledge on the Ecuadorian Native Amerindian groups and the unique South American Y-chromosome haplogroup C3-MPB373 through the analysis of up to 23 Y-chromosome STRs (Y-STRs) and several Y-SNPs in a sample of 527 Ecuadorians from 7 distinct populations and geographic areas, including Kichwa and non-Kichwa Native Amerindians, Mestizos and Afro-Ecuadorians. Our results reveal the presence of C3-MPB373 both in the Amazonian lowland Kichwa with frequencies up to 28 % and, for the first time, in notable proportions in Kichwa populations from the Ecuadorian highlands. The substantially higher frequencies of C3-MPB373 in the Amazonian lowlands found in Kichwa and Waorani individuals suggest a founder effect in that area. Notably, estimates for the time to the most recent common ancestor (TMRCA) in the range of 7.2-9.0 kya point to an ancient origin of the haplogroup and suggest an early Holocene expansion of C3-MPB373 into South America. Finally, the pairwise genetic distances (RST) separate the Kichwa Salasaka from all the other Native Amerindian and Ecuadorian groups, indicating a so far hidden diversity among the Kichwa-speaking populations and suggesting a more southern origin of this population. In sum, our study provides a more in-depth knowledge of the male genetic structure of the multiethnic Ecuadorian population, as well as a valuable reference dataset for forensic use.