Download Epigenetic Clock and Biological Age Steve Horvath, Professor of

Epigenetic Clock and Biological Age
Steve Horvath, Professor of Human Genetics and Biostatistics, University of California, Los Angeles
The DNA methylation based biomarker of aging known as the "epigenetic clock" can be used to measure
the DNA methylation (DNAm) age of any human (or chimpanzee) tissue, cell type, or fluid that contains
DNA with the exception of sperm. DNAm age of blood has been shown to predict all-cause mortality in
later life, even after adjusting for known risk factors, which suggests that it relates to the biological aging
process. Similarly, markers of physical and mental fitness are also found to be associated with the
epigenetic clock (lower abilities associated with age acceleration).
DNA methylation age has the following properties: first, it is close to zero for embryonic and induced
pluripotent stem cells; second, it correlates with cell passage number; third, it gives rise to a highly
heritable measure of age acceleration; and, fourth, it is applicable to chimpanzee tissues.
I illustrate the utility of this novel biomarker of aging by studying obesity, HIV infection, Alzheimer's
disease, Parkinson's disease syndrome X, and supercentenarians.
Analysis of 6,000 cancer samples from 32 datasets showed that cancer types exhibit significant positive
and negative age acceleration. Low age-acceleration of cancer tissue is associated with a high number of
somatic mutations and TP53 mutations, while mutations in steroid receptors greatly accelerate DNA
methylation age in breast cancer.
These results suggest that we are close to achieving a long standing milestone in aging research: the
development of an accurate measure of tissue age or even biological age.
Main reference
Horvath S (2013) DNA methylation age of human tissues and cell types. Genome Biology 2013, 14:R115
Correction: http://genomebiology.com/2013/14/10/R115/comments
Wikipedia: https://en.wikipedia.org/wiki/Biological_clock_(aging)