Run-specific limits of quantitation and detection: an alternative to minimum peak height thresholds. (Dr. Dan Krane, Biological Sciences, Wright State University)

STR-based DNA profiling is an exceptionally sensitive analytical technique that is often used to obtain results at the very limits of its sensitivity. The challenge of reliably distinguishing between signal and noise in such situations is one that has been rigorously addressed in numerous other analytical disciplines. However, an inability to accurately determine the height of electropherogram baselines has caused forensic DNA profiling laboratories to utilize alternative approaches. Minimum thresholds established during laboratory validation studies have become the de facto standard for distinguishing between reliable signal and noise/technical artifacts. These minimum peak height thresholds generally fail to consider variability in the sensitivity of instruments, reagents, and the skill of human analysts involved in the DNA profiling process over the course of time. Software made publicly available by the National Center for Biotechnology Information now provides an alternative means of establishing limits of detection and quantitation that is more consistent with those employed in other analytical disciplines. Analyses of the electropherogram data associated with the positive, negative and reagent blank controls included in 50 different capillary electrophoresis runs suggest that this approach could be employed to objectively determine run-specific thresholds for use in forensic DNA casework.

Materials

Presentation

J. Gilder, T. Doom, K. Inman, and D. Krane. Run-specific limits of detection and quantitation for STR-based DNA testing. Journal of Forensic Sciences. 2007;52(1):97-101.

National Center for Biotechnology Information (NCBI). BatchExtract Software Download Page.

V. Thomsen, D. Schatzlein, and D. Mercuro. Limits of Detection in Spectroscopy. Spectroscopy 2003;18(12):112-114.