Concordance testing between Powerplex ESI 16 Fast System and VeriFiler Express

Area of Science:

• Forensic Science
• Genetics
• Molecular Biology

Background:

• Short tandem repeat (STR) kits are crucial for DNA profiling in forensic science.
• Variations in allele calls between different STR kits can hinder data sharing and database comparisons.
• Expanding analyzed loci is necessary for handling degraded samples, low DNA quantities, and complex mixtures.

Purpose of the Study:

• To compare genotyping data between the VeriFiler™ Express and Powerplex™ ESI FAST STR kits.
• To quantify the discordance rates and types of mismatches observed between the two kits.
• To highlight the importance of addressing inter-kit variability in DNA analysis.

Main Methods:

• Genotyping of 1568 DNA samples using both VeriFiler™ Express and Powerplex™ ESI FAST kits.
• Comparative analysis of allele data generated by the two STR kits.
• Identification and categorization of discordant genotyping results.

Main Results:

• A discordance rate of 1.27% was observed between the VeriFiler™ Express and Powerplex™ ESI FAST kits.
• Allele dropout mismatch occurred in 0.89% of samples, and additional fixed-size third alleles in 0.38%.
• Observed discordance rates exceeded previously reported rates for the VeriFiler™ Express kit.

Conclusions:

• Significant inter-kit variability exists in STR genotyping, necessitating careful validation.
• DNA laboratories and genetic-match search systems must consider these inconsistencies for accurate profile interpretation.
• Standardization or robust cross-validation protocols are essential for reliable DNA database management and casework.