Collaborative EDNAP exercise on the IrisPlex system for DNA-based prediction of human eye colour

Area of Science:

• Forensic Genetics
• Human Genetics
• Biotechnology

Background:

• The IrisPlex system utilizes DNA analysis to predict human eye color.
• It combines a validated multiplex genotyping assay with a statistical model based on extensive genotype and phenotype data.
• Previous studies indicate high precision for blue and brown eye color prediction, with lower accuracy for other shades.

Purpose of the Study:

• To rigorously assess the IrisPlex system's performance at an international level.
• To evaluate the reproducibility, robustness, and accuracy of the IrisPlex assay and prediction model.
• To demonstrate the system's implementability across diverse forensic laboratories.

Main Methods:

• An international collaborative exercise involving 21 laboratories was conducted.
• Testing included analysis of blood and saliva samples, simulated casework samples (artificially degraded), and participant-selected subjects.
• Genotyping accuracy and eye color phenotype prediction were assessed across three distinct tasks.

Main Results:

• Across Tasks 1 and 2, 99.2% of genotypes were correctly generated, with only 0.1% leading to incorrect eye color predictions.
• Task 1 showed 99.4% genotype accuracy and 99% eye color prediction accuracy.
• Task 2 achieved 98.7% genotype accuracy and 96.2% eye color prediction accuracy, even with degraded DNA.
• Task 3 reported 96% eye color prediction accuracy across 100 samples.

Conclusions:

• The IrisPlex system demonstrates high success rates in both genotyping and eye color phenotyping.
• The assay is reproducible and robust, and the model accurately predicts blue and brown eye color from DNA.
• The study confirms the IrisPlex system's ease of implementation and applicability in global forensic laboratories.