STRmix™ collaborative exercise on DNA mixture interpretation

Forensic Sci Int Genet. 2019 May:40:1-8. doi: 10.1016/j.fsigen.2019.01.006. Epub 2019 Jan 15.

Abstract

An intra and inter-laboratory study using the probabilistic genotyping (PG) software STRmix™ is reported. Two complex mixtures from the PROVEDIt set, analysed on an Applied Biosystems™ 3500 Series Genetic Analyzer, were selected. 174 participants responded. For Sample 1 (low template, in the order of 200 rfu for major contributors) five participants described the comparison as inconclusive with respect to the POI or excluded him. Where LRs were assigned, the point estimates ranging from 2 × 104 to 8 × 106. For Sample 2 (in the order of 2000 rfu for major contributors), LRs ranged from 2 × 1028 to 2 × 1029. Where LRs were calculated, the differences between participants can be attributed to (from largest to smallest impact): This study demonstrates a high level of repeatability and reproducibility among the participants. For those results that differed from the mode, the differences in LR were almost always minor or conservative.

Keywords: Forensic DNA interpretation; Inter-laboratory study; Intra-laboratory study; Probabilistic genotyping; STRmix.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Cooperative Behavior
  • DNA / analysis*
  • DNA Fingerprinting*
  • Gene Frequency
  • Genotype
  • Humans
  • Laboratories
  • Likelihood Functions
  • Microsatellite Repeats*
  • Reproducibility of Results
  • Software*

Substances

  • DNA