The relative location of DMRs (differentially methylated regions), IGF2 (insulin-like growth factor 2), ICR, H19, and enhancer were presented in Fig. 1A. On the paternal allele (Fig. 1B left), ICR is hypermethylated and prevents the expression of H19. In contrast, on maternal allele (Fig. 1B right), ICR is unmethylated and CCCTC binding factor (CTCF) is recruited. The enhancer binds the H19 promoter and activates its expression.