Epigenetics for biomedical sciences

Epigenetics is fundamental to the development and maintenance of cellular phenotypes. Epigenetic status is inherited by the next cell generation and is changeable during the process of cellular differentiation. DNA methylation, in association with histone modifications and chromatin condensation, is a major epigenetic event that causes gene silencing. Every cell type or tissue has a unique DNA methylation profile comprising at least thousands of tissue-dependent differentially methylated regions (T-DMRs), suggesting that the epigenetic changes at T-DMRs underlie cellular differentiation. Genome-wide epigenetic information is called the epigenome. Disruption of the normal epigenome produces aberrant cells with prolonged abnormal phenotypes. Epimutation may be more common than previously thought considering there are numerous T-DMRs in the mammalian genome. Mutation and epimutation are inherited by the next cell generation, and both continue throughout life. However, epimutation is reversible, and drug treatment could potentially reverse the epigenetic status. Analysis of the epigenome will provide insight into novel advances in diagnosis and treatment of, as well as drug development for, complex chronic diseases.