In recent years, DNA methylation has become widely used in forensic genetics as a biomarker for estimating chronological age. Advances in high throughput technologies have enabled the identification of numerous age associated CpG sites and the development of tissue-specific chronological age prediction models with mean errors about ± 3-4 years. However, in forensic casework the biological origin of a trace is often unknown, and traces may comprise mixtures of tissues, such as cigarette butts containing epithelial cells and saliva. In this context, multi tissue models are a necessary advancement, although most currently available approaches remain tissue specific.

In the current study, we identified CpG markers exhibiting consistent age correlations across multiple tissues. Two scenarios were considered as potential applications when grouping the tissues of interest: i) criminal investigations and ii) Disaster Victim Identification (DVI). Using publicly available datasets from GEO datasets, we selected age associated CpGs shared across i) blood, saliva, and buccal cells; and ii) muscle, bone, and blood. The selected markers were subsequently validated using an independent dataset comprising the studied tissues and additional tissues of forensic relevance, such as cartilage.

The study received funding from the European Union’s Horizon Europe Programme under Grant agreement no. 101225631. Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or REA.

Authors

• Adrián Ambroa-Conde (Forensic Genetics Unit, Institute of Forensic Sciences, Universidade de Santiago de Compostela, Spain)
• Miguel Boullón-Cassau (Forensic Genetics Unit, Institute of Forensic Sciences, Universidade de Santiago de Compostela, Spain)
• Mafalda Silva (Forensic Genetics Unit, Institute of Forensic Sciences, Universidade de Santiago de Compostela, Spain)
• Aleksandra Pisarek-Pacek (Institute of Zoology and Biomedical Research, Jagiellonian University, Poland)
• Ewelina Pośpiech (Department of Genomics and Forensic Genetics, Pomeranian Medical University, Poland)
• Kamila Marszałek (Department of Genomics and Forensic Genetics, Pomeranian Medical University, Poland)
• Walther Parson (Institute of Legal Medicine, Medizinische Universität Innsbruck, Innsbruck, Austria; Forensic Science Program, The Pennsylvania State University, University Park, PA, United States of America)
• Antonia Heidegger (Institute of Legal Medicine, Medizinische Universität Innsbruck, Poland)
• Wojciech Branicki (Institute of Zoology and Biomedical Research, Jagiellonian University; Institute of Forensic Research in Kraków, Poland)
• M Victoria Lareu (Forensic Genetics Unit, Institute of Forensic Sciences, Universidade de Santiago de Compostela, Spain)
• Ana Freire-Aradas (Forensic Genetics Unit, Institute of Forensic Sciences, Universidade de Santiago de Compostela, Spain)