PhenoAge

Definition

Phenotypic Age (often shortened to PhenoAge) is a mortality-risk-derived composite reported in units of years. It is calculated from chronological age and nine routine blood biomarkers selected from a larger candidate set. DNAm PhenoAge is a distinct epigenetic estimator: it uses methylation at 513 CpG sites and was trained in whole blood to predict the clinical Phenotypic Age measure. [1] [2]

Why It Matters in Ageing Research

Phenotypic Age was developed from mortality-related clinical information rather than by fitting chronological age alone. In cohort research, the clinical and DNA-methylation measures have been tested for associations with mortality, morbidity, and functional outcomes beyond chronological age. Those associations support their use as research biomarkers, but do not make either measure a direct reading of an individual's underlying ageing process. [1] [2]

Common Confusion

• Phenotypic Age and DNAm PhenoAge are related but not interchangeable: one uses clinical biomarkers, while the other was trained to predict it from DNA methylation.
• A value expressed in "years" is a model-derived risk scale, not evidence that every tissue is literally that old.
• Age-acceleration analyses may use a simple difference from chronological age or a model residual; studies should state which definition they use.
• A higher or lower result is neither a diagnosis nor a validated clinical target for an individual treatment decision.

Related Reading

• Biological Age
• Epigenetic Clocks
• DNA Methylation

References

1. Liu, Z., Kuo, P. L., Horvath, S., Crimmins, E., Ferrucci, L., & Levine, M. (2018). A new aging measure captures morbidity and mortality risk across diverse subpopulations from NHANES IV: A cohort study. https://doi.org/10.1371/journal.pmed.1002718
2. Levine, M. E., Lu, A. T., Quach, A., Chen, B. H., Assimes, T. L., Bandinelli, S., Hou, L., Baccarelli, A. A., Stewart, J. D., Li, Y., Whitsel, E. A., Wilson, J. G., Reiner, A. P., Aviv, A., Lohman, K., Liu, Y., Ferrucci, L., & Horvath, S. (2018). An epigenetic biomarker of aging for lifespan and healthspan. https://doi.org/10.18632/aging.101414