DNA methylation correlates of chronological age in diverse human tissue types.
Level 4 - case-series / case-control
Cross-sectional observational study of post-mortem human tissue samples (by design analogy, not clinical CEBM).
PubMed 39118140 · doi:10.1186/s13072-024-00546-6
What was done
An epigenome-wide association study was performed using Illumina EPIC array DNA methylation data from 961 tissue samples across nine human tissue types (breast, lung, colon, ovary, prostate, skeletal muscle, testis, whole blood, and kidney) from the Genotype-Tissue Expression (GTEx) project. The authors identified age-associated CpG sites (false discovery rate < 0.05), assessed genomic feature enrichment, and correlated methylation with local transcript levels to identify age-related expression quantitative trait methylation (age-eQTMs).
What was found
Age-associated CpG sites were identified in eight tissues, with none detected in skeletal muscle (n = 47). Across all tissues, 162,002 unique hypermethylated and 90,626 hypomethylated CpG sites were identified, of which 130,137 (80%) of hypermethylated and 74,703 (82%) of hypomethylated sites were restricted to a single tissue type. Despite site-level tissue specificity, enrichment patterns across genomic features were consistent across tissues: hypermethylated sites were enriched in polycomb-repressed regions and CpG islands, while hypomethylated sites occurred in non-CpG islands and enhancers. Shared age-eQTMs across multiple tissues included regions near CDKN2A, HENMT1, and VCWE.
Why it matters
This study shows that while specific DNA methylation changes with age are predominantly tissue-specific, the underlying chromatin mechanisms and key regulatory genes linked to aging are shared across diverse human tissues.
Limits
The study is cross-sectional and derived from post-mortem donor samples, precluding longitudinal tracking of within-person epigenetic drift. Bulk tissue profiling means cell-type composition changes with age cannot be separated from cell-intrinsic methylation shifts. Some tissue subsets (notably skeletal muscle, n = 47) had smaller sample sizes that limited statistical power.
Cited by
- supports DNA methylation sites that lose methylation with aging are enriched in enhancer regions.