Evaluation of samples comprising minute amounts of DNA. Issue 5 (September 2015)

• Record Type: Journal Article
• Authors: Benschop, Corina C.G.; Haned, Hinda; Yoo, Seong Yeon; Sijen, Titia
• Is Part Of: Science & justice. Volume 55:Issue 5(2015)
• Page Start: 316
• Page End: 322
• Publication Date: 2015-09
• Subjects: Forensic science -- Low template DNA -- Trace DNA -- Enhanced profiling -- Likelihood ratios -- Relevance of the evidence; Forensic sciences -- Periodicals; Criminal investigation -- Periodicals; Forensic Medicine -- Periodicals; Jurisprudence -- Periodicals; Criminalistique -- Périodiques; Enquêtes criminelles -- Périodiques; Criminal investigation; Forensic sciences; Electronic journals; Periodicals; 363.2505
• DOI: 10.1016/j.scijus.2015.05.002
• Languages: English
• ISSNs: 1355-0306

Abstract

Abstract: Minute amounts of DNA representing only few diploid cells, may be interrogated using enhanced DNA profiling, which will be accompanied by stochastic amplification effects. Notwithstanding, a weight of evidence statistic may be calculated using current interpretation software. In this study, we profiled single donor, two- and three-person samples having only 3 pg to 12 pg of DNA per contributor using both standard and enhanced capillary electrophoresis (CE) injection settings. Likelihood ratios (LRs) were computed using LRmix Studio, compared for both types of profiles and examined in relation to the amount of DNA, drop-out level, number of detected alleles, peak heights and reproducibility of alleles. Especially for DNA profiles that were generated using enhanced CE, the obtained LRs could indicate strong evidence in favour of the prosecution (log10 (LR) > 6), also when the amount of DNA represented about half of a diploid cell equivalent in the amplification. These results illustrate that an assessment of the criminalistic relevance of a sample carrying minute amounts of DNA is essential prior to applying enhanced interrogation techniques and/or calculating a weight of evidence statistic. Highlights: DNA samples with one to three donors were prepared using 3–12 pg per contributor. Standard and enhanced profiling was used for these minute amounts of DNA. Enhanced profiling resulted in lower drop-out rates and higher reproducibility. LR values were often – but not always – higher with enhanced profiling. The relevance of enhanced profiling and LR computations is discussed.