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

Population data for 12 X-STRs loci in Malaysian Malay and Chinese populations

The utilization of X-chromosome short tandem repeats (X-STRs) for human identification particularly in resolving complex kinship cases has been advocated. Since, forensic statistical parameters vary among different populations, and because the X-STRs population data representing the diverse population of Peninsular Malaysia remain unavailable, the specific attempt reported here for the Malays (n = 224) and Chinese (n = 201) populations appears forensically relevant to support the evidential value of the 12 X-STRs markers for human identification in Malaysia. Results derived from the Qiagen Investigator® Argus X-12 kit revealed that DXS10135 as the most polymorphic locus with high genetic diversity, polymorphic information content, heterozygosity as well as power of exclusion. Based on allele frequencies, the combined power of discrimination as well as the mean exclusion chance (MECKrüger, MECKishida, MECDesmarais and MECDesmaraisDuo) values for the Malays and Chinese were individually ≥0.999995532964908. As for the combined power of discrimination as well as the mean exclusion chance (MECKrüger, MECKishida, MECDesmarais and MECDesmaraisDuo) calculated based on haplotype frequencies, the values were ≥0.9999986410567 for the Malays and Chinese populations. In addition, results from the genetic distance, neighbor-joining phylogenetic tree and principal component analysis revealed close biogeographical distributions of the studied populations with other South East Asian populations. Hence, the utilization of the X-STRs data for identifying individuals among the Malays and Chinese populations in Peninsular Malaysia for forensic application appears as highly supported.

Population analysis of complete mitogenomes for 334 samples from El Salvador

The use of mitochondrial DNA (mtDNA) in the field of forensic genetics is widely spread mainly due to its advantages when identifying highly degraded samples. In this sense, massive parallel sequencing has made the analysis of the whole mitogenome more accessible, noticeably increasing the informativeness of mtDNA haplotypes. The civil war (1980-1992) in El Salvador caused many deaths and disappearances (including children) all across the country and the economic and social instability after the war forced many people to emigration. For this reason, different organizations have collected DNA samples from relatives with the aim of identifying missing people. Thus, we present a dataset containing 334 complete mitogenomes from the Salvadoran general population. To the best of our knowledge, this is the first publication of a nationwide forensic-quality complete mitogenome database of any Latin American country. We found 293 different haplotypes, with a random match probability of 0.0041 and 26.6 mean pairwise differences, which is similar to other Latin American populations, and which represent a marked improvement from the values obtained with just control region sequences. These haplotypes belong to 54 different haplogroups, being 91% of them of Native American origin. Over a third (35.9%) of the individuals carried at least a heteroplasmic site (excluding length heteroplasmies). Ultimately, the present database aims to represent mtDNA haplotype diversity in the general Salvadoran populations as a basis for the identification of people that disappeared during or after the civil war.

A review of ancestrality and admixture in Latin America and the caribbean focusing on native American and African descendant populations

Genomics can reveal essential features about the demographic evolution of a population that may not be apparent from historical elements. In recent years, there has been a significant increase in the number of studies applying genomic epidemiological approaches to understand the genetic structure and diversity of human populations in the context of demographic history and for implementing precision medicine. These efforts have traditionally been applied predominantly to populations of European origin. More recently, initiatives in the United States and Africa are including more diverse populations, establishing new horizons for research in human populations with African and/or Native ancestries. Still, even in the most recent projects, the under-representation of genomic data from Latin America and the Caribbean (LAC) is remarkable. In addition, because the region presents the most recent global miscegenation, genomics data from LAC may add relevant information to understand population admixture better. Admixture in LAC started during the colonial period, in the 15th century, with intense miscegenation between European settlers, mainly from Portugal and Spain, with local indigenous and sub-Saharan Africans brought through the slave trade. Since, there are descendants of formerly enslaved and Native American populations in the LAC territory; they are considered vulnerable populations because of their history and current living conditions. In this context, studying LAC Native American and African descendant populations is important for several reasons. First, studying human populations from different origins makes it possible to understand the diversity of the human genome better. Second, it also has an immediate application to these populations, such as empowering communities with the knowledge of their ancestral origins. Furthermore, because knowledge of the population genomic structure is an essential requirement for implementing genomic medicine and precision health practices, population genomics studies may ensure that these communities have access to genomic information for risk assessment, prevention, and the delivery of optimized treatment; thus, helping to reduce inequalities in the Western Hemisphere. Hoping to set the stage for future studies, we review different aspects related to genetic and genomic research in vulnerable populations from LAC countries.

A forensic population database in El Salvador: 58 STRs and 94 SNPs

We have genotyped the 58 STRs (27 autosomal, 24 Y-STRs and 7 X-STRs) and 94 autosomal SNPs in Illumina ForenSeq™ Primer Mix A in a sample of 248 men and 143 women from El Salvador, Central America. Regional division (Centro, Oriente, Occidente) showed in almost all cases F_ST values not significantly different from 0, and further analyses were applied only to the undivided, country-wide population. The overall random match probability (RMP) decreased from 6.79 × 10^-31 in length-based genotypes in the 27 autosomal STRs to 1.47 × 10^-34 in repeat-sequence based genotypes. Combining the autosomal loci in this set, RMP reaches 2.97 × 10^-70. In a population genetic analysis, El Salvador showed the lowest F_ST values with US Hispanics both for autosomal and X-STRs; however, it was much closer to Native Americans for the latter than for the former, in accordance with the well-known gender-biased admixture that created most Latin American populations.