Fig. 1.

An illustration of the TAD fusion where a deletion can affect the genome structure. The original genome (upper) has two TADs separating by a TAD boundary. Any locus of one TAD can interact with other loci in the same TAD (e.g., the enhancer and gene B of TAD₂). But a locus cannot interact with any other locus of the other TAD (e.g., gene A of TAD₁ and the enhancer of TAD₂). In the mutant genome (lower), two original TADs are fused into one TAD since the TAD boundary is removed by the deletion. Thus, any two loci in the fusion TAD can interact although they do not interact in the original genome (e.g., the enhancer and gene A)