The H19 DMD is required to prevent interactions between the maternal endodermal enhancers and the Igf2 promoters. The 3C analysis was carried out on samples from a H19Δ3.8 kb-5′H19 × B6(CAST7) cross. (A) Top, schematic of the H19Δ3.8 kb-5′H19 allele (see Fig. 2 for details), with 3.8 kb upstream of the H19 promoter removed. Bottom, representative gel image of 3C PCR products: D, digested with NlaIII, which distinguishes paternal (P) from maternal (M) alleles; 3C, non-digested PCR product; -L, no ligase control; +, positive control. When the H19Δ3.8 kb-5′H19 allele is inherited maternally, the endodermal enhancers on the maternal chromosome interact with the whole H19 region. (B) Top, schematic of the Igf2 locus (see Fig. 3 for details). Bottom, representative gel image of 3C PCR products digested with HaeIII, which distinguishes paternal (P) from maternal (M) alleles.