Epigenetics: Its role in aging, diseases and biological age estimation

Epigenetics, a new emerging field in biomedical science, is defined as the study of heritable changes in gene function that do not change the DNA sequence, also describing the mechanisms that enable cells to respond quickly to environmental changes and providing a link between genes and the environment (Egger et al. 2004, Turan et al. 2010). DNA is wrapped around clusters (octamers) of globular histone proteins to form nucleosomes, which are organized into chromatin. Changes to the structure of chromatin influence gene expression because when chromatin is condensed, genes are inactivated, while they are expressed when chromatin is opened (Peterson and Laniel 2004, Rountree et al. 2001). These changes are controlled by reversible epigenetic patterns of DNA methylation and histone modifications (Feinberg and Tycko 2004). Alterations in these patterns can dysregulate gene expression, leading to diseases and accelerated aging.