title: Further evidence for population specific differences in the effect of DNA markers and gender on eye colour prediction in forensics.
abstract: The genetics of eye colour has been extensively studied over the past few years, and the identified polymorphisms have been applied with marked success in the field of Forensic DNA Phenotyping. A picture that arises from evaluation of the currently available eye colour prediction markers shows that only the analysis of HERC2-OCA2 complex has similar effectiveness in different populations, while the predictive potential of other loci may vary significantly. Moreover, the role of gender in the explanation of human eye colour variation should not be neglected in some populations. In the present study, we re-investigated the data for 1020 Polish individuals and using neural networks and logistic regression methods explored predictive capacity of IrisPlex SNPs and gender in this population sample. In general, neural networks provided higher prediction accuracy comparing to logistic regression (AUC increase by 0.02-0.06). Four out of six IrisPlex SNPs were associated with eye colour in the studied population. HERC2 rs12913832, OCA2 rs1800407 and SLC24A4 rs12896399 were found to be the most important eye colour predictors (p < 0.007) while the effect of rs16891982 in SLC45A2 was less significant. Gender was found to be significantly associated with eye colour with males having ~1.5 higher odds for blue eye colour comparing to females (p = 0.002) and was ranked as the third most important factor in blue/non-blue eye colour determination. However, the implementation of gender into the developed prediction models had marginal and ambiguous impact on the overall accuracy of prediction confirming that the effect of gender on eye colour in this population is small. Our study indicated the advantage of neural networks in prediction modeling in forensics and provided additional evidence for population specific differences in the predictive importance of the IrisPlex SNPs and gender.
authors.affiliation: Institute of Zoology, Faculty of Biology and Earth Sciences, Jagiellonian University, Kraków, Poland. ewelina.pospiech@uj.edu.pl.|Malopolska Centre of Biotechnology, Jagiellonian University, Kraków, Poland. ewelina.pospiech@uj.edu.pl.
authors.forename: Ewelina
authors.initials: E
authors.lastname: Pośpiech
authors.affiliation: Faculty of Mathematics and Computer Science, Nicolaus Copernicus University, Toruń, Poland.
authors.forename: Joanna
authors.initials: J
authors.lastname: Karłowska-Pik
authors.affiliation: Faculty of Mathematics and Computer Science, Nicolaus Copernicus University, Toruń, Poland.
authors.forename: Bartosz
authors.initials: B
authors.lastname: Ziemkiewicz
authors.affiliation: Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Kraków, Poland.
authors.forename: Magdalena
authors.initials: M
authors.lastname: Kukla
authors.affiliation: Department of Dermatology, Collegium Medicum of the Jagiellonian University, Kraków, Poland.
authors.forename: Małgorzata
authors.initials: M
authors.lastname: Skowron
authors.affiliation: Department of Dermatology, Collegium Medicum of the Jagiellonian University, Kraków, Poland.
authors.forename: Anna
authors.initials: A
authors.lastname: Wojas-Pelc
authors.affiliation: Malopolska Centre of Biotechnology, Jagiellonian University, Kraków, Poland.
authors.forename: Wojciech
authors.initials: W
authors.lastname: Branicki
mesh_terms: D017920:Antiporters / Q000235:genetics; D005127:Eye Color / Q000235:genetics*; D005260:Female; D005828:Genetics, Population; D020662:Guanine Nucleotide Exchange Factors / Q000235:genetics; D006801:Humans; D016015:Logistic Models; D008297:Male; D026901:Membrane Transport Proteins / Q000235:genetics; D016571:Neural Networks, Computer; D011044:Poland; D020641:Polymorphism, Single Nucleotide; D012737:Sex Factors; D044767:Ubiquitin-Protein Ligases
chemical_list: D017920:Antiporters; D020662:Guanine Nucleotide Exchange Factors; D026901:Membrane Transport Proteins; C489600:OCA2 protein, human; C470570:SLC24A4 protein, human; C118566:HERC2 protein, human; D044767:Ubiquitin-Protein Ligases
keywords: Eye colour prediction; Forensic DNA Phenotyping (FDP); Gender effect; IrisPlex SNPs; Logistic regression; Neural networks