The human genome comprises approximately 30000 genes needed for the formation and function of approximately 1 Million proteins in the human body. Differentiation leads to the deactivation of genes that are not needed in the specific tissues or cells. To regulate the cell specific gene expression in normal cells epigenetic modifications work in concert with genetic mechanisms. In contrast to genetic mutations, epigenetics encompasses the wide range of heritable changes in gene expression that do not result from alteration in the DNA sequence itself. A dysregulation of epigenetic modifications results in diseases such as cancer or autoimmune diseases. Since these epigenetic modifications of the DNA and the histones are reversible they are good targets for novel therapeutic intervention.