A selection guide for the new generation 6-dye DNA profiling systems.

The Federal Bureau of Investigation (FBI) has recently expanded the CODIS core loci from the existing 13 to 20 as a new guideline, and laboratories from the US are required to comply with the new regulation before uploading or conducting identity search in the national database. The expanded CODIS format, which shares all the core loci commonly used in the European countries and the US, not only increases international compatibility, but also reduces the number of adventitious matches, and hence facilitates international law enforcement and counterterrorism endeavours. Here, we review the key performance measures of three new STR amplification systems with 6-dye chemistry, namely, the Investigator 24plex QS Kit from QIAGEN, the GlobalFiler™ PCR Amplification Kit from Applied Biosystems™, and the PowerPlex Fusion 6C System from Promega. Our results have demonstrated that GlobalFiler displays the highest sensitivity among the tested kits, whereas Investigator 24plex shows a higher tolerance to common PCR inhibitors including Humic acid and Tannic acid. GlobalFiler and Fusion 6C, on the other hand, yield DNA profiles with better heterozygous peak height and intra-colour signal balance. Both GlobalFiler and Investigator 24plex exhibit slightly higher sensitivity than Fusion 6C in the profiling of minor components in DNA mixture, but the latter displays a higher consistency in the preservation of the mixture ratio. In summary, our work has demonstrated that these three profiling systems have their different performance features, and hence it is recommended that laboratories should select the most suitable kits according to their own requirements and operational needs.