Structural mutations in enhancers: (i) IGFBP5 gene is regulated by its enhancer. When a small stretch in the enhancer is deleted which harboured the CTCF motif, the enhancer activity from the region is lost and gene is down-regulated. IGFBP5 being a tumour-suppressor gene leads to increased risk of cancer. (ii) An oncogene TAL1, has some basal expression in the wild type condition. Mutations lead to the gain of Myb motifs which facilitate the birth of a super-enhancer which up-regulates TAL1 expression and thus leading to increased susceptibility to cancer. (iii) Mutations in the enhancer of AR gene lead to the amplification of the region harbouring the enhancer which leads to increased expression of androgen receptor leading to increased prostate cancer risk. (iv) An enhancer is present physically far from the TERT gene. Rearrangement places the enhancer in close physical proximity to the TERT oncogene leading to its activation.