Accurate estimates of population-specific STR allele frequencies are crucial for forensic casework, particularly in highly admixed populations such those from Brazil. This work reports population data and evaluates the forensic performance of 23 autosomal STR loci in a sample of 676 unrelated individuals from the State of Rio de Janeiro, Southeastern Brazil, using the Investigator 26Plex® QS kit. No loci showed deviations from Hardy–Weinberg equilibrium, and high levels of genetic diversity were observed across all STRs, resulting in a combined discrimination power of 0.9999999999 and a combined exclusion power of 0.99999999998. Population differentiation was assessed through pairwise FST analyses between the Rio de Janeiro dataset and published data from other Brazilian populations, representing all five Brazilian geographic regions. Non-significant genetic differentiation was detected in comparison with populations from the Northeast and Central-West regions. In comparison with populations from the North region, significant differences were obtained for TH01 and FGA. The largest FST values were found in comparison with populations from the South region, with significant differentiation values for 12 out of the 22 loci compared, likely reflecting regional ancestry variation. A concordance analysis performed in a subset of 276 samples previously typed with the AmpFℓSTR™ Identifiler™ kit showed high agreement between the genotypes of the overlapping loci, including for a triallelic pattern at TPOX. Two samples showed D16S539 allelic imbalance when genotyped with the Investigator kit. Genotype discrepancies between the two kits were found in 4 samples, attributable to null alleles at D21S11 (2 samples) and D19S433 (1 sample), when amplified with the Investigator, and a null allele at D8S1179, when amplified with the Identifiler. The overall results demonstrate the suitability and robustness of the Investigator 26Plex® system for forensic identification and kinship analysis in Rio de Janeiro population.

Authors

• Leonor Gusmão (DNA Diagnostic Laboratory (LDD), State University of Rio de Janeiro (UERJ), Brazil)
• Alessandra Dias (DNA Diagnostic Laboratory (LDD), State University of Rio de Janeiro (UERJ), Brazil)
• Myriam Lima (DNA Diagnostic Laboratory (LDD), State University of Rio de Janeiro (UERJ), Brazil)
• João Marreiro (DNA Diagnostic Laboratory (LDD), State University of Rio de Janeiro (UERJ), Brazil)
• Patrícia Domingues (DNA Diagnostic Laboratory (LDD), State University of Rio de Janeiro (UERJ), Brazil)
• Elizeu Carvalho (DNA Diagnostic Laboratory (LDD), State University of Rio de Janeiro (UERJ), Brazil)