Effect of Type of Degraded DNA Samples on Human Eye Color Prediction

Abstract

Single nucleotide polymorphisms (SNPs) are the most abundant genetic markers in the human genome. SNPs are used in forensics for predicting the externally visible characteristics of a given individual based on a sample of DNA alone. In this study, we tested degraded DNA samples to determine the eye color prediction accuracy of the IrisPlex system. We used five years old bloodstains and UVC exposed (30 and 60 min) DNA samples. PCR and electrophoresis were performed. The multinomial logistic regression model statistics is applied for eye color prediction. We observed allele and locus drop-outs on both bloodstains stored for five years and UVC exposed samples. The brown and blue eye colors were correctly predicted for reference and degraded samples. The intermediate eye colors were predicted to be brown or inconclusive. The degradation by aging bloodstains or UVC exposure, is differently affected the prediction accuracy depending on the informativeness of the SNPs. This study showed that the prediction of the eye color is highly accurate for the blue and brown eye colored individuals. However, the IrisPlex prediction accuracy could be influenced by the old and degraded samples.