Epigenome: The Program For Human Health And Disease

Abstract

A colleague of mine once took a small vial out of his pocket, and placed it on the table in front of him before he sat down for a conference. As the conference drew to a close, he carefully picked up the vial, and announced, “This is a vial of DNA, and in the past two days, it hasn’t done a damn thing!”. Like a computer, DNA is impotent without its software, the epigenome, telling it when, where and how to work. ‘Epigenome’ simply means ‘above the genome’, and it refers to a heritable chemical marking system, comprised of DNA methylation, histone marks and noncoding RNA species, that alters gene expression without relying on a disturbance in the underlying genetic code. In contrast to the genome, the epigenome is different in every cell type in the body. The ability to modify epi genetic programming is indeed critical for cellular differentiation and the development of complex living organisms from a single set of genomic instructions. The epigenome is also more malleable than the genome, producing a conduit by which the environment can readily and rapidly affect change in gene function. Such variation can be acted upon by natural selection, ultimately resulting in adaptive responses; however, it can also increase susceptibility to diseases.