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Open Access Research article

A ranking index for quality assessment of forensic DNA profiles

Johannes Hedman12, Ricky Ansell13 and Anders Nordgaard14*

Author Affiliations

1 Swedish National Laboratory of Forensic Science (SKL), SE-581 94 Linköping, Sweden

2 Department of Applied Microbiology, Lund University, SE-221 00 Lund, Sweden

3 Department of Physics, Chemistry and Biology, Linköping University, SE-581 83 Linköping, Sweden

4 Department of Computer and Information Science, Linköping University, SE-581 83 Linköping, Sweden

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BMC Research Notes 2010, 3:290  doi:10.1186/1756-0500-3-290

Published: 9 November 2010

Abstract

Background

Assessment of DNA profile quality is vital in forensic DNA analysis, both in order to determine the evidentiary value of DNA results and to compare the performance of different DNA analysis protocols. Generally the quality assessment is performed through manual examination of the DNA profiles based on empirical knowledge, or by comparing the intensities (allelic peak heights) of the capillary electrophoresis electropherograms.

Results

We recently developed a ranking index for unbiased and quantitative quality assessment of forensic DNA profiles, the forensic DNA profile index (FI) (Hedman et al. Improved forensic DNA analysis through the use of alternative DNA polymerases and statistical modeling of DNA profiles, Biotechniques 47 (2009) 951-958). FI uses electropherogram data to combine the intensities of the allelic peaks with the balances within and between loci, using Principal Components Analysis. Here we present the construction of FI. We explain the mathematical and statistical methodologies used and present details about the applied data reduction method. Thereby we show how to adapt the ranking index for any Short Tandem Repeat-based forensic DNA typing system through validation against a manual grading scale and calibration against a specific set of DNA profiles.

Conclusions

The developed tool provides unbiased quality assessment of forensic DNA profiles. It can be applied for any DNA profiling system based on Short Tandem Repeat markers. Apart from crime related DNA analysis, FI can therefore be used as a quality tool in paternal or familial testing as well as in disaster victim identification.