Chromosome folding: driver or passenger of epigenetic state?

Despite a growing understanding of how epigenetic marks such as histone modifications locally modify the activity of the chromatin with which they are associated, we know little about how marked regions on different parts of the genome are able to intercommunicate to effect regulation of gene expression programs. Recent advances in methods that systematically map pairwise chromatin interactions have uncovered important principles of chromosome folding, which are tightly linked to the epigenetic mark profiles and, hence, functional state of the underlying chromatin fiber.