Topographically Associating Domain

Topographically Associating Domain

Drawing of TAD

Researchers found that the more densely coiled the DNA is inside TADs (as in the right image compared to the left) the greater the gene expression, likely due to the fact that more genes are brought into contact with their regulatory elements. TADs are areas on the genome within which DNA sequences physically interact with each other more frequently than with sequences outside the TAD. 

IMAGE: Qunhua Li