PowerPlex Fusion System による STR 型検査の法科学的評価

抄録

  Because of its high usefullness and discrimination power, short tandem repeat (STR) analysis has been playing the most important role in forensic DNA examinations for more than 10 years. Recently, Promega has developed a PowerPlex Fusion system which genotypes 22 autosomal STR, Amelogenin and DYS391 loci. In this study, we validated the Fusion system for forensic purposes using the 3500 xL with a threshold value of 175 RFU and the 3130 xl with 150 RFU.
  The PCR cycle was adjusted to 28 cycles to give an optimal peak height from 1 ng DNA. The reproducibility of the electrophoresis for the 3500 xL was improved by changing the run voltage from 15 kV to 13 kV. When 13 anomalous samples that tended to be designated as off ladder (OL) at D12S391 locus were injected at least 10 times, the 3500 xL with 15 kV gave the highest observation of OL, followed by the 3500 xL with 13 kV and the 3130 xl with 15 kV. Most of the spectral pull-up ratios were within 2.68% for the 3500 xL, and within 5.85% for the 3130 xl. The spectral pull-up from red (CXR-ET) to yellow (TMR-ET) was more obviously generated by the 3130 xl than by the 3500 xL. We also examined sensitivity, mixed DNA, base line noise in electrophoresis, peak height ratios, stutter ratios, 20% cut-off filter, aged bloodstains, animal DNAs, and tolerance to PCR inhibitors. We concluded that the Fusion system could be used as a STR kit for forensic purposes. However, cautions should be taken, since 1) the inter locus and the intra color peak balances were slightly worse than those of the Identifier plus kit, 2) the loci of high molecular weight tended not to be detected in degraded samples, and 3) the OL designation was occasionally observed at the D12S391 locus especially when using the 3500 xL.