Exploring STR Signal in the Single- and Multicopy Number Regimes: Deductions From an In Silico Model of the Entire DNA Laboratory Process

• NCJ Number: 252099
• Author(s): Ken R. Duffy, Neil Gurram, Kelsey C. Peters, Genevieve Wellner, Catherine M. Grgicak
• Date Published: December 2016
• Length: 14 pages
• Agencies: NIJ-Sponsored
• Award: Establishing Exclusion Criteria and the Significance of Inclusion: Developing Tools for the Interpretation of Complex DNA Mixtures

Annotation

This article describes a model that allows rapid in silico simulation of electropherograms from multicontributor DNA samples and enables detailed investigations of involved scenarios.

Abstract

Short tandem repeat (STR) profiling from DNA samples has long been the bedrock of human identification. The laboratory process is composed of multiple procedures that include quantification, sample dilution, PCR, electrophoresis, and fragment analysis. The end product is a short tandem repeat electropherogram comprised of signal from allele, artifacts, and instrument noise. In order to optimize or alter laboratory protocols, a large number of validation samples must be created at significant expense. As a tool to support that process and to enable the exploration of complex scenarios without costly sample creation, a mechanistic stochastic model that incorporates each of the aforementioned processing features is described in this article. An implementation of the model that is parameterized by extensive laboratory data is publicly available. To illustrate its utility, the model was employed in order to evaluate the effects of sample dilutions, injection time, and cycle number on peak height, and the nature of stutter ratios at low template. The model's findings were verified by comparison with experimentally generated data. (Publisher abstract modified)