Extended Data Figure 10: Bimodality and monoallelic distributions.

a–c, Three scenarios of emergence of bimodal methylation pattern distributions. A monoallelic pattern is predicted to be maintained in monoclonal populations, while loci that are differentially methylated in a subpopulation may become coherent following a clonal bottleneck. Alternatively, rapid methylation turnover can combine with slow fluctuation in a local chromosomal state to generate a methylation landscape that is either methylated or unmethylated, without clonal stability. d, Examples of monoallelic patterns that are conserved in clonal populations for both ES cells and fibroblasts. e, Chromosomal distributions of monoallelic patterns. f, Examples of loci developing bimodal methylation in the fibroblast population but not in ES cells. g, Chromosomal distribution of fibroblast-specific monoallelic loci, reflecting strong enrichment of the X chromosome, as well as clustering in several autosomal loci. h, Epiallelic noise at 0 is defined as the fraction of partially methylated patterns in the loci with methylation content less than 50%. The noise at 1 is defined reciprocally (Methods). Shown are the cumulative distributions for epiallelic noise in high variance loci (blue). Controls are computed using loci with less than 20% average methylation (for controlling noise 0) and over 80% average methylation (for controlling noise 1).