Validation of the Investigator 24plex QS Kit: a 6-dye multiplex PCR assay for forensic application in the Chinese Han population

The Investigator 24plex QS Kit (QIAGEN, Hilden, Germany) is a 6-dye fluorescent chemistry short tandem repeat (STR) polymerase chain reaction (PCR) amplification system that simultaneously amplifies 20 of the expanded Combined DNA Index System (CODIS) core STR loci, SE33, DYS391, and the standard sex-determining locus, amelogenin, as well as two special internal performance quality sensor controls (QS1 and QS2), which are included in the primer mix to check the PCR performance. This study was designed to be a pilot evaluation of this STR-PCR kit in a Chinese Han population regarding the PCR conditions, sensitivity, precision, accuracy, repeatability, reproducibility, and concordance; tolerance to PCR inhibitors; applicability to real “forensic-type” samples; species specificity; mixture, balance and stutter analyses, and utility in a population investigation. The exhaustive validation studies demonstrated that the Investigator 24plex QS system is accurate, sensitive and robust for STR genotyping. In addition, these genetic markers in the population data in our study indicated that they can also be useful for forensic identification and paternity testing in the Chinese Han population.