Abstract
In analyzing a DNA mixture sample, the measured peak areas of alleles of STR markers
amplified using the polymerase chain-reaction (PCR) technique provide valuable information
concerning the relative amounts of DNA originating from each contributor to the mixture.
This information can be exploited for the purpose of trying to predict the genetic
profiles of those contributors whose genetic profiles are not known. The task is non-trivial,
in part due to the need to take into account the stochastic nature of peak area values.
Various methods have been proposed suggesting ways in which this may be done. One
recent suggestion is a probabilistic expert system model that uses gamma distributions
to model the size and stochastic variation in peak area values. In this paper we carry
out a statistical analysis of the gamma distribution assumption, testing the assumption
against synthetic peak area values computer generated using an independent model that
simulates the PCR amplification process. Our analysis shows the gamma assumption works
very well when allelic dropout is not present, but performs less and less well as
dropout becomes more and more of an issue, such as occurs, for example, in Low Copy
Template amplifications.
Keywords
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Article info
Publication history
Published online: February 17, 2009
Accepted:
January 7,
2009
Received in revised form:
January 6,
2009
Received:
July 18,
2008
Identification
Copyright
© 2009 Elsevier Ireland Ltd. Published by Elsevier Inc. All rights reserved.
