Allele-specific aberration of imprinted domain chromosome architecture associates with large offspring syndrome [WGBS]

Large offspring syndrome (LOS) and Beckwith-Wiedemann syndrome are a similar epigenetic congenital overgrowth conditions in ruminants and humans, respectively. We have reported global loss-of-imprinting, methylome epimutations, and global misregulation of genes in LOS. However, less than 4% of gene misregulation can be explained with short range (<20Kb) alterations in DNA methylation. Therefore, we hypothesized that methylome epimutations in LOS affect chromosome architecture which results in misregulation of genes located at distances >20Kb in cis and also in trans (other chromosomes). Our analyses focused on two imprinted domains that frequently show misregulation in these syndromes, namely KvDMR1 and IGF2R. Using bovine fetal fibroblasts, we identified CTCF binding at IGF2R but not KvDMR1, and allele-specific chromosome architecture of these domains in controls. In LOS, analyses identified erroneous long-range contacts and clustering tendency in the direction of expression of misregulated genes. In conclusion, altered chromosome architecture is involved in the etiology of LOS. Overall design: Whole genome bisulfite sequencing (WGBS) for skin fibroblast primary cells derived from four control and four LOS bovine day 105 fetuses.