NCJ Number
248136
Journal
Forensic Science International Genetics Volume: 12 Dated: September 2014 Pages: 1-11
Date Published
September 2014
Length
11 pages
Annotation
Since there are few empirical studies that have determined allelic drop-out probabilities in low template (LT) DNA profiles, this project characterized patterns of allele drop-out in single-source samples using both universal and run-specific analytical thresholds.
Abstract
This project demonstrated that the use of a likelihood ratio (LR) that incorporates empirically estimated allelic drop-out probabilities provides a reliable means for extracting additional information from LT forensic DNA profiles. As expected, researchers found fewer instances of apparent drop-out when using a lower (run-specific) detection threshold. In addition, a positive correlation was found between allele drop-out and allele length, even in good-quality samples. Logistic regression was used to model the fraction of alleles that dropped out of a profile as a function of the average height of the detected peaks. The equation derived from the logistic regression model allowed researchers to estimate the expected drop-out probabilities, suggesting that the estimate of the drop-out probability are accurate and useful. This trend held even when using the data from the PowerPlex 16 typing system to estimate the drop-out probability for an Identifiler profile and vice versa. 4 tables, 6 figures, and 50 references