Genomic imprinting

Genomic imprinting is parent-of-origin-dependent gene expression caused by epigenetic marks. At imprinted genes, one parental allele is silenced or expressed less than the other.

DNA methylation: DNA methylation is the addition of methyl groups to DNA, often altering gene expression without changing the DNA sequence. Differential methylation at imprinting control regions helps silence one parental allele.
IGF2: IGF2 is a gene encoding insulin-like growth factor 2, a protein involved in fetal growth. In many tissues, the paternal IGF2 allele is expressed while the maternal allele is silenced.
Prader–Willi syndrome: Prader–Willi syndrome is a genetic disorder involving hypotonia, developmental differences, and abnormal appetite regulation. Loss of expression from the paternal chromosome 15 imprinted region causes the syndrome.
Helen Crouse: Helen Crouse was an American geneticist who studied chromosome behavior in insects and mammals. Her 1960s work on mammalian chromosome inheritance helped establish parent-specific developmental effects.
X-chromosome inactivation: X-chromosome inactivation is the silencing of one X chromosome in cells of organisms with two X chromosomes. It is chromosome-wide dosage compensation, whereas imprinting usually affects particular genes or regions.
Genomic imprinting control region: A genomic imprinting control region is a DNA segment whose parent-specific epigenetic state regulates nearby imprinted genes. Its inherited methylation state can determine which parental allele is active.
H19: H19 is an imprinted gene that produces a long noncoding RNA and lies near IGF2 on chromosome 11. Its maternal expression contrasts with paternal IGF2 expression at the same locus.
Angelman syndrome: Angelman syndrome is a neurodevelopmental disorder characterized by severe developmental delay, speech impairment, and movement difficulties. Loss of maternal UBE3A expression in neurons is a common cause.
August Weismann: August Weismann was a German biologist who proposed a distinction between germ cells and somatic cells. The germline distinction frames how heritable imprint marks can be reset between generations.
Position-effect variegation: Position-effect variegation is mosaic gene silencing caused by a gene's relocation near heterochromatin. Its silencing depends on chromosomal context, not whether an allele came from the mother or father.

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