To improve the ability to differentiate related males in forensic cases, new Y-STR genotyping kits have been increasing their number of loci with high mutation rates. This work aims to evaluate the performance of the Investigator ARGUS Y-28 QS kit in genotyping forensic samples, as well as to estimate its discrimination power in the Brazilian admixed population. With this goal, blood and saliva samples were collected from 238 unrelated males residing in different States of the country, under informed consent. Using the original protocol provided with the kit, two parameters were assessed: (i) sensitivity and (ii) male/female mixtures performance. The results demonstrate that the ARGUS Y-28 kit is capable of generating complete profiles with a DNA concentration of 125 pg. In male/female mixtures, complete Y-STR profiles were detected with proportions of up to 1:1500 in the presence of 250 ng of female DNA. Tests conducted for population databasing showed that a final PCR volume of 5 μL and 0.5 ng of DNA results in complete and clear profiles, with allele detection levels between 3000 and 10000 RFU. An analysis of 238 Brazilian individuals revealed 235 unique haplotypes, with just three of them being shared by two individuals each. In an additional sample, the ARGUS Y-28 amplified a DYS389II allele that was null with the PowerPlex Y23 kit, revealing a mutation at the primer annealing. Using the Arlequin software, a discrimination power of 99.99% was estimated for the Brazilian population. In conclusion, the kit shows a good performance in forensic analyses, providing reliable results for all markers, even with DNA concentrations as low as 125 pg. Moreover, robust results were achieved with low concentrations of male DNA, even in the presence of high amounts of female DNA, which is crucial in sexual violence cases. The discrimination power obtained indicates that the kit is informative for Y-chromosomal forensic analysis in admixed Brazilian samples.

Authors

• Eduarda Q. Santarosa (DNA Diagnostic Laboratory (LDD), State University of Rio de Janeiro (UERJ), Brazil)
• Laís Leal (DNA Diagnostic Laboratory (LDD), State University of Rio de Janeiro (UERJ), Brazil)
• Leonor Gusmão (DNA Diagnostic Laboratory (LDD), State University of Rio de Janeiro (UERJ), Brazil)