This book gives an in-depth overview on nuclear structure and function. It clearly shows that the epigenome and the three-dimensional organization of the nucleus are not independent properties. The intimate relationship between the location and the epigenetic modifications of gene loci is highlighted. Finally, it shows that the complex three-dimensional organization of the nucleus is not just of academic interest: The structure, composition and function of virtually all of the sub-nuclear compartments identified so far can be implicated to a list of human genetic diseases. Hence, a detailed elucidation of how these domains are assembled and function will provide new opportunities for therapeutic intervention in clinical practice.