Genomic Imprinting: It Takes Two to Make a Thing Go Right

How does genomic imprinting silence one parent's genes, and why does that balance matter for normal development? Epigenetics lets our cells modify gene expression without touching the underlying DNA sequence, and genomic imprinting is one of its most surprising tricks: it switches off genes on just one of the two parental alleles, using DNA methylation and post-translational histone modifications so that only the mother's or only the father's copy stays active. To see what happens when that balance breaks, this video walks through Sheila Barton and colleagues' 1991 mouse study, where nuclear transplantation built androgenetic (AG) eggs carrying two paternal genomes and gynogenetic (GG) eggs carrying two maternal genomes. The results are striking — AG embryos grew with scoliotic spines, distorted and fused ribs, and enlarged hearts, while GG embryos showed the reciprocal pattern, with growth reduced and different tissues favoured. Together the data point to imprinting setting a careful #GeneDosage that developing embryos genuinely depend on, a principle that reaches all the way to human conditions like Prader-Willi and #AngelmanSyndrome, where imprinting on chromosome 15 meets a deletion. It's a clear window into why #GenomicImprinting is essential for normal growth and development. Educational content — not medical advice Creator: Elizabeth Au References Barton SC, Ferguson-Smith AC, Fundele R, Surani MA. 1991. Influence of paternally imprinted genes on development. Development 113(2):679–687. https://doi.org/10.1242/dev.113.2.679 Barton SC, Surani MA, Norris ML. 1984. Role of paternal and maternal genomes in mouse development. Nature 311(5984):374–376. https://doi.org/10.1038/311374a0 Cattanach BM, Kirk M. 1985. Differential activity of maternally and paternally derived chromosome regions in mice. Nature 315(6019):496–498. https://doi.org/10.1038/315496a0 DeChiara TM, Robertson EJ, Efstratiadis A. 1991. Parental imprinting of the mouse insulin-like growth factor II gene. Cell 64(4):849–859. https://doi.org/10.1016/0092-8674(91)... Mann JR, Stewart CL. 1991. Development to term of mouse androgenetic aggregation chimeras. Development 113(4):1325–1333. https://doi.org/10.1242/dev.113.4.1325 McGrath J, Solter D. 1984. Completion of mouse embryogenesis requires both the maternal and paternal genomes. Cell 37(1):179–183. https://doi.org/10.1016/0092-8674(84)... Nicholls RD, Knoll JH, Butler MG, Karam S, Lalande M. 1989. Genetic imprinting suggested by maternal heterodisomy in nondeletion Prader-Willi syndrome. Nature 342(6247):281–285. https://doi.org/10.1038/342281a0 Surani MA, Barton SC, Norris ML. 1984. Development of reconstituted mouse eggs suggests imprinting of the genome during gametogenesis. Nature 308(5959):548–550. https://doi.org/10.1038/308548a0 Thomson JA, Solter D. 1988. The developmental fate of androgenetic, parthenogenetic, and gynogenetic cells in chimeric gastrulating mouse embryos. Genes Dev 2(10):1344–1351. https://doi.org/10.1101/gad.2.10.1344