The IrisPlex system is a DNA-based test system for the prediction of human eye colour from biological samples and consists of a single forensically validated multiplex genotyping assay together with a statistical prediction model that is based on genotypes and phenotypes from thousands of individuals. IrisPlex predicts blue and brown human eye colour with, on average, >94% precision accuracy using six of the currently most eye colour informative single nucleotide polymorphisms (HERC2 rs12913832, OCA2 rs1800407, SLC24A4 rs12896399, SLC45A2 (MATP) rs16891982, TYR rs1393350, and IRF4 rs12203592) according to a previous study, while the accuracy in predicting non-blue and non-brown eye colours is considerably lower. In an effort to vigorously assess the IrisPlex system at the international level, testing was performed by 21 laboratories in the context of a collaborative exercise divided into three tasks and organised by the European DNA Profiling (EDNAP) Group of the International Society of Forensic Genetics (ISFG). Task 1 involved the assessment of 10 blood and saliva samples provided on FTA cards by the organising laboratory together with eye colour phenotypes; 99.4% of the genotypes were correctly reported and 99% of the eye colour phenotypes were correctly predicted. Task 2 involved the assessment of 5 DNA samples extracted by the host laboratory from simulated casework samples, artificially degraded, and provided to the participants in varying DNA concentrations. For this task, 98.7% of the genotypes were correctly determined and 96.2% of eye colour phenotypes were correctly inferred. For Tasks 1 and 2 together, 99.2% (1875) of the 1890 genotypes were correctly generated and of the 15 (0.8%) incorrect genotype calls, only 2 (0.1%) resulted in incorrect eye colour phenotypes. The voluntary Task 3 involved participants choosing their own test subjects for IrisPlex genotyping and eye colour phenotype inference, while eye photographs were provided to the organising laboratory and judged; 96% of the eye colour phenotypes were inferred correctly across 100 samples and 19 laboratories. The high success rates in genotyping and eye colour phenotyping clearly demonstrate the reproducibility and the robustness of the IrisPlex assay as well as the accuracy of the IrisPlex model to predict blue and brown eye colour from DNA. Additionally, this study demonstrates the ease with which the IrisPlex system is implementable and applicable across forensic laboratories around the world with varying pre-existing experiences.

Department of Forensic and Analytical Science School of Biomedical Sciences King's College London United Kingdom

Department of Forensic Biology Norwegian Institute of Public Health Oslo Norway

Department of Forensic Genetics and Forensic Toxicology National Board of Forensic Medicine Linköping Sweden

Department of Forensic Genetics Institute of Criminalistics Prague Czech Republic

Department of Forensic Medicine Hjelt Institute University of Helsinki Helsinki Finland

Department of Forensic Medicine Hjelt Institute University of Helsinki Helsinki Finland; Institute of Applied Genetics Department of Forensic and Investigative Genetics University of North Texas Health Science Center Fort Worth TX USA

Department of Forensic Molecular Biology Erasmus MC University Medical Centre Rotterdam Rotterdam The Netherlands

Department of Human Biological Traces Netherlands Forensic Institute The Hague The Netherlands

Forensic Genetics Laboratory Institute of Legal Medicine Università Cattolica del Sacro Cuore Rome Italy

Forensic Genetics Unit Institute of Legal Medicine University of Santiago de Compostela Santiago de Compostela Spain

Forensic Services Department Victoria Police Macleod Victoria Australia

Institute of Biology and Medical Genetics 1st Faculty of Medicine Charles University Prague and General University Hospital Prague Prague Czech Republic; Institute of Forensic Medicine and Toxicology 1st Faculty of Medicine Charles University Prague Prague Czech Republic

Institute of Forensic Science Ministry of the Interior Department of Biology and DNA Analysis Slovenská Lupca Slovakia

Institute of Legal Medicine Faculty of Medicine University of Cologne Cologne Germany

Institute of Legal Medicine Innsbruck Medical University Innsbruck Austria

Institute of Legal Medicine University of Zurich Zurich Switzerland

Kriminaltechnik Bundeskriminalamt Wiesbaden Germany

Laboratoire d'Anthropologie Moléculaire Université de Strasbourg Institut de Médecine Légale Strasbourg France

Material Measurement Laboratory National Institute of Standards and Technology Gaithersburg MD USA

School of Biological Sciences Flinders University Adelaide South Australia Australia

Section of Forensic Genetics Department of Forensic Medicine Faculty of Health Sciences University of Copenhagen Copenhagen Denmark

Section of Forensic Genetics Institute of Forensic Research Kraków Poland

Section of Forensic Genetics Institute of Forensic Research Kraków Poland; Department of Genetics and Evolution Institute of Zoology Jagiellonian University Kraków Poland

Serviço de Genética e Biologia Forense Delegação do Centro Instituto Nacional de Medicina Legal Coimbra Portugal

Swedish National Laboratory of Forensic Science Linköping Sweden

References provided by Crossref.org