Fig. 3

A post-hoc rationale for the Weibull distribution. According to the ABC model [18] of gene activation and models of chromatin compaction [14, 15], the chance that a particular enhancer (E1-E4) is in contact with the promoter of a particular gene (“Gene”) is proportional to distance^−γ (that is, distance to the power -γ, where γ has a value of about 1) from the enhancer to the promoter. In a scenario where all enhancers are equally active, a particular gene will be most strongly influenced by the closest enhancer (E2 in this figure). A Weibull model, as observed empirically in this analysis, can result from such a “superposition” of power-law distributions [17]