Abstract
DNA phenotyping is a rapidly developing area of research in forensic biology. Externally
visible characteristics (EVCs) can be determined based on genotype data, specifically
based on single nucleotide polymorphisms (SNPs). These SNPs are chosen based on their
association with genes related to the phenotypic expression of interest, with known
examples in eye, hair, and skin color traits. DNA phenotyping has forensic importance
when unknown biological samples at a crime scene do not result in a criminal database
hit; a phenotypic profile of the sample can therefore be used to develop investigational
leads. IrisPlex, an eye color prediction assay, has previously shown high prediction
rates for blue and brown eye color in a Dutch European population. The objective of
this work was to evaluate its utility in a North American population. We evaluated
six SNPs included in the IrisPlex assay in population sample collected from a USA
college campus. We used a quantitative method of eye color classification based on
(RGB) color components of digital photographs of the eye taken from each study volunteer
so that each eye was placed in one of three eye color categories: brown, intermediate,
or blue. Objective color classification was shown to correlate with basic human visual
determination making it a feasible option for use in future prediction assay development.
Using these samples and various models, the maximum prediction accuracies of the IrisPlex
system after allele frequency adjustment was 58% and 95% brown and blue eye color
predictions, respectively, and 11% for intermediate eye colors. Future developments
should include incorporation of additional informative SNPs, specifically related
to the intermediate eye color, and we recommend the use of a Bayesian approach as
a prediction model as likelihood ratios can be determined for reporting purposes.
Keywords
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Article info
Publication history
Published online: December 16, 2013
Accepted:
December 4,
2013
Received in revised form:
August 27,
2013
Received:
April 25,
2013
Identification
Copyright
© 2013 Elsevier Ireland Ltd. Published by Elsevier Inc. All rights reserved.
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- Corrigendum to “Evaluation of the IrisPlex DNA-based eye color prediction assay in a United States population” [Forensic Sci. Int. Genet. (2014) 111–117]Forensic Science International: GeneticsVol. 24
- PreviewAfter further scrutiny of the genotype and eye color data of the 200 samples used in the dataset while analyzing it for post-published purposes, some inconsistencies were noted which the authors would like to further report here. There were 9 samples (5 in training set, 4 in the validation set) that had their genotypes shifted by one sample in the data so that the true genotype of the sample was not correctly aligned. The erroneously shifted genotypes were corrected and allele frequencies were recalculated for 4 SNPs.
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