In order to assist forensic DNA analysts in their assessment of the performance of commonly used short-tandem-repeat (STR) amplification kits, the National Forensic Science Technology Center (NFSTC) evaluated the performance of eight STR amplification kits: Applied Biosystems' Ampf&STR Profiler Plus ID kit, Cofiler kit, Identifiler kit, MiniFiler kit and Yfiler kit, and Promega's PowerPlex 16 system, PowerPlex Y system and PowerPlex S5 system.
The kits were assessed for sensitivity, peak ratios at heterozygous loci, baseline noise, stutter ratio, and amplification artifacts. The evaluation found that PowerPlex 16 exhibited greater sensitivity than Identifiler, Profiler Plus and Cofiler and MiniFiler exhibited greater sensitivity than PowerPlex S5. Identifiler, Profiler Plus, and Cofiler demonstrated comparable peak heights to each other for each concentration. All of the amplification kits, with the exception of PowerPlex 16, maintain a 60 percent heterozygosity ratio for 1 ng and 0.5 ng concentrations. Identifiler maintained heterozygosity ratios of 60 percent more frequently than PowerPlex 16 for concentrations from 0.0625 ng to 1 ng. Profiler Plus and Cofiler maintained heterozygosity ratios more frequently than Identifiler, for the lower concentrations in the dilution series (0.078 ng to 0.125 ng). PowerPlex Y displayed higher RFU range than Yfiler at each concentration. Cofiler, Identifiler and PowerPlex S5 displayed less stochastic effects when compared to kits of similar size. The mixture sample with a 1:5 ratio yielded a full profile for the minor donor for all amplification kits except PowerPlex Y. Cofiler and PowerPlex S5 are the only two kits that displayed a full profile for the minor donor down to 1:8 ratio. Areas for improvement in the eight kits are outlined, and training requirements and health and safety issues are discussed. 5 figures