Analysis of mixed DNA profiles from the RapidHIT™ ID platform using probabilistic genotyping software STRmix™

Abstract

Rapid DNA instruments are gaining interest in the forensic community as a means to generate DNA profile information more quickly than standard laboratory workflows, and with the potential to be carried out at the scene where samples are taken. Due to the many years that DNA profiles have been generated in a standard laboratory workflow, there have been numerous studies into profiling performance. These have flowed into probabilistic means of evaluating DNA profiles produced in those laboratories. In this study we examined the DNA profiling performance of the RapidHIT™ ID system on artificial mixtures constructed from raw DNA, mixtures constructed from body fluids, and touch DNA samples. We calibrated the probabilistic genotyping system STRmix™ for use on results produced by the RapidHIT ID system. Identical DNA samples were split, with half analysed on the RapidHIT ID system and the other half analysed in the standard laboratory workflow. Profiles produced from these paired samples were compared with regards to their composition and discrimination power. In general, profiles produced using the RapidHIT ID system showed good discrimination power, but less than those produced via the standard laboratory workflow. This is the expected trade-off for the advantages of speed and portability.

Keywords: DNA mixtures; GlobalFiler; Probabilistic genotypes; Rapid DNA; RapidHIT ID; STRmix.