Analytical Thresholds and Sensitivity: Establishing RFU Thresholds for Forensic DNA Analysis

• NCJ Number: 243738
• Author(s): Joli Bregu,, Danielle Conklin,, Elisse Coronado,, Robin W. Cotton,, Catherine M. Grgicak,, Margaret Terrill, M.S.F.S.
• Date Published: January 2013
• Length: 10 pages
• Agencies: NIJ-Sponsored
• Award: TRAINING COURSES FOR THE FORENSIC PRACTITIONER: LABORATORY EXPERIENCE WITH BIOLOGICAL EVIDENCE

Annotation

Determining appropriate analytical thresholds (ATs) for forensic DNA analysis is critical to maximize allele detection.

Abstract

Determining appropriate analytical thresholds (ATs) for forensic DNA analysis is critical to maximize allele detection. In this study, six methods to determine ATs for forensic DNA purposes were examined and compared. Four of the methods rely on analysis of the baseline noise of a number of negatives, while two utilize the relationship between relative fluorescence unit signal and DNA input in the polymerase chain reaction (PCR) derived from a dilution series ranging from 1 to 0.06 ng. Results showed that when a substantial mass of DNA (i.e., less than 1 ng) was amplified, the baseline noise increased, suggesting the application of an AT derived from negatives should only be applied to samples with low levels of DNA. Further, the number and intensity of these noise peaks increased with increasing injection times, indicating that to maximize the ability to detect alleles, ATs should be validated for each post-PCR procedure employed. Abstract published by arrangement with John Wiley & Sons.