A Tcl/Tk graphical user interface for simple DNA mixtures resolution using allele peak heights/ or areas information

Description

The mastermix function launches a Tcl/Tk graphical user interface dedicated to the resolution of two-person DNA mixtures using allele peak heights/ or areas information. mastermix is the implementation of a method developed by Gill et al (see the references section), and previously programmed into an Excel macro by Dr. Peter Gill.

Usage

1

Details

mastermix is a Tcl/Tk graphical user interface implementing a method developed by Gill et al (1998) for simple mixtures resolution, using allele peak heights or areas information.

This method searches through simulation the most likely combination(s) of the contributors' genotypes. Having previously obtained an estimation for the mixture proportion, it is possible to reduce the number of possible genotype combinations by keeping only those supported by the observed data. This is achieved by computing the sum of square differences between the expected allelic ratio and the observed allelic ratio, for all possible mixture combinations. The likelihood of peak heights (or areas), conditional on the combination of genotypes, is high if the residuals are low. Genotype combinations are thus selected according to the peak heights with the highest (conditioned) likelihoods.

mastermix offers a graphical representation of the simulation for three models:
-The two allele model: at a given locus, two alleles are observed in the DNA stain.
-The three allele model: at a given locus, three alleles are observed in the DNA stain.
-The four allele model: at a given locus, four alleles are observed in the DNA stain.

A left-click on each button launches a simulation dialog window for the corresponding model, while a right-click opens the corresponding help page.

Note

-Each implemented model can either be launched using the mastermix interface, or the A2.simu, A3.simu and A4.simu functions, depending on the considered model.
-For the computational details, please see forensim tutorial at http://forensim.r-forge.r-project.org/misc/forensim-tutorial.pdf.

Author(s)

Hinda Haned h.haned@nfi.minvenj.nl

References

Gill P, Sparkes P, Pinchin R, Clayton, Whitaker J, Buckleton J. Interpreting simple STR mixtures using allele peak areas. Forensic Sci Int 1998;91:41-5.

See Also

A2.simu, A3.simu and A4.simu

Examples

1

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