Within the 15q15.1 chromatin contact domain, chromosome conformation capture–on-chip with sequencing (4C-seq) in the MEC1 CLL cell line showed a high frequency of three-dimensional contacts between the viewpoint (adjacent to rs539846) and the distal end of the predicted super-enhancer, with both points overlapping regions of RELA and CTCF binding (Figure 2B). Here, CTCF is linked to B-cell chronic lymphocytic leukemia.