2025 Biomarkers of Aging Conference

DNA methylation has emerged as an important biomarker in ageing research, offering information to assess biological age  The 6 whilst improving the understanding of underlying mechanisms of ageing. Among the most well-known tools is the Horvath clock1, which leverages methylation patterns at specific CpG sites to estimate biological age with remarkable accuracy. These epigenetic clocks have transformed our understanding of age-related processes and disease risk, yet  they traditionally rely on the detection of modified cytosine using methylation arrays. However, a known limitation of array-based ageing biomarkers is that modified cytosine comprises distinct 5mC and 5hmC methylation states with different functional roles2. 5mC is associated with regions of closed chromatin and reduced gene expression whereas  5hmC has a dynamic role in the activation of gene expression, driving cellular plasticity and determining cell fate.  

Recent advances in epigenomic profiling, particularly the development of the 6-base  sequencing technology duet evoC3, enable the differentiation between 5mC and 5hmC alongside identification of the canonical DNA bases A, C, G & T. Using duet evoC,  we revisit the Horvath clock methylation biomarkers using genomic DNA extracted from tissue samples and cfDNA from donors of various ages. We uncover differential contributions from 5mC and 5hmC, revealing a more nuanced epigenetic ageing landscape than was previously possible.  

Future ageing clocks and biomarkers that incorporate both 5mC and 5hmC promise to improve precision and reveal additional mechanistic insight into ageing, potentially uncovering novel pathways of age-related change and therapeutic intervention.