The low-template-DNA (stochastic) threshold-Its determination relative to risk analysis for national DNA databases

Peter Gill*, Roberto Puch-Solis, James Curran

*Corresponding author for this work

Research output: Contribution to journalArticle

Abstract

Although the low-template or stochastic threshold is in widespread use and is typically set to 150-200 rfu peak height, there has been no consideration on its determination and meaning. In this paper we propose a definition that is based upon the specific risk of wrongful designation of a heterozygous genotype as a homozygote which could lead to a false exclusion. Conversely, it is possible that a homozygote {a,a} could be designated as {a,F} where 'F' is a 'wild card', and this could lead to increased risk of false inclusion. To determine these risk levels, we analysed an experimental dataset that exhibited extreme drop-out using logistic regression. The derived probabilities are employed in a graphical model to determine the relative risks of wrongful designations that may cause false inclusions and exclusions. The methods described in this paper provide a preliminary solution of risk evaluation for any DNA process that employs a stochastic threshold.

Original languageEnglish
Pages (from-to)104-111
Number of pages8
JournalForensic Science International: Genetics
Volume3
Issue number2
DOIs
Publication statusPublished - 1 Mar 2009

Keywords

  • Extreme drop-out
  • Low-copy-number
  • Low-level-DNA (stochastic) threshold
  • National DNA database
  • STR

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