DNA Methylation Clocks May Be Inaccurate for Some Organs, Study Finds
How DNA Methylation Clocks Measure Aging
A recent study published in Aging (Aging-US) explores the accuracy of DNA methylation clocks—biological tools that estimate a person’s age based on chemical changes in their DNA. These clocks are widely used in forensic science, epigenetics, and longevity research to predict age-related diseases and assess lifestyle impacts on aging. However, new findings suggest that while these clocks work well for blood samples, they may be less reliable for other tissues, such as the lungs, colon, and kidneys.
Study Findings: Accuracy Varies Across Tissues
Researchers from the University of Chicago and the University of Pittsburgh analyzed data from 973 tissue samples collected through the Genotype-Tissue Expression (GTEx) project. They tested eight different DNA methylation clocks across nine human tissue types, including the lungs, prostate, ovaries, skeletal muscle, and kidneys.
Their results revealed that biological age estimates differed significantly depending on the tissue. Blood samples provided the most accurate results, but some organs showed surprising variations. For example:
- Testis and ovary tissues appeared younger than expected.
- Lung and colon tissues appeared older.
The study found that clocks trained solely on blood samples, such as the Hannum clock, were the least reliable for other tissues. Even the widely used Horvath clock, designed for multiple tissue types, showed inconsistencies.
Implications for Aging Research and Health Monitoring
These findings suggest that aging does not occur uniformly across all organs. Standard DNA methylation clocks may not always provide accurate biological age estimates outside of blood samples. To improve aging predictions, researchers propose developing tissue-specific epigenetic clocks that can assess biological age more accurately for different organs.
Such advancements could:
- Enhance medical diagnostics
- Improve age-related disease prevention
- Offer better tools for personalized health monitoring
The study emphasizes the need for larger research efforts with more diverse tissue samples. By refining these aging clocks, scientists can gain deeper insights into how aging affects different organs and develop more effective strategies for promoting healthy aging.
