Optimal Modularity Method (OMM) for unbiased TADs detection in chromatin contact maps of single cells

It becomes clear that chromosome contact maps, constructed via genome-wide chromosome capture technique Hi-C, in principle, might provide the full information on spatial structure of chromosomes at different stages of cellular cycle. According to the analyses of the population-averaged maps, the spatial conformation of interphase chromosomes features a set of, so-called, topologically-associated domains (TADs), in which the density of contacts well exceeds the one calculated in the adjacent regions [1]. Even though the definition of a TAD is not precise and in practice often includes some phenomenological cutoff parameters for density, the crucial issue concerning stability of TADs boundaries along the chromosome sequence in each individual cell cannot be addressed in the framework of population-averaged Hi-C maps.