Autosomal str allele frequencies, forensic parameters and population structure in four underrepresented indigenous groups from Paraguay

Indigenous populations in Paraguay have historically been excluded from forensic genetic reference databases. In current casework, allele frequency estimates for Indigenous individuals are typically derived from admixed Paraguayan datasets, which may introduce statistical bias and reduce the accuracy of human identification and kinship analyses. Addressing this gap is essential to ensure equitable and appropriate forensic interpretation. Here, we present the first comprehensive autosomal STR reference dataset specifically developed for Indigenous communities in Paraguay. A total of 276 individuals from four distinct groups: Nivaclé (n = 119), Enxet Sur/Mbya (n = 68), Mbya (n = 30), and Aché (n = 59) were genotyped for 23 STR loci commonly used in forensic practice. All markers presented high heterozygosity, strong discrimination power, and minimal missing data, supporting their robustness for use in casework and database applications. Population structure analyses indicated that more than 90% of the genetic variation occurs within populations, with only moderate differentiation among them. These findings reinforce the need to treat Indigenous groups as independent reference populations rather than assuming representativeness from admixed national samples. The dataset generated in this study fills a critical gap in South American forensic genetics by incorporating historically underrepresented communities into national reference resources. By improving the accuracy and fairness of match probability estimates, this work contributes to strengthening forensic reliability and promoting a more equitable justice system for Indigenous peoples in Paraguay.