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epigenetic process that leads to inactivation of paternal or maternal allele of certain genes susceptible to epigenetic regulation; accounts, among others, for the Angelman and Prader-Willi syndromes.
Farlex Partner Medical Dictionary © Farlex 2012
ge·nom·ic im·print·ing(jē-nō'mik im'print-ing)
Epigenetic process that leads to inactivation of paternal or maternal allele of certain genes susceptible to epigenetic regulation; accounts, among others, for the Angelman and Prader-Willi syndromes.
Medical Dictionary for the Health Professions and Nursing © Farlex 2012
genomic imprintingThe concept, derived from an increasing body of compelling evidence, that the expression of some of the genes depends on whether they have been derived from the father or from the mother. It has been shown, for instance, that chromosomal deletion in chromosomes of parental origin may differ in their effect from the same deletion in the homologous chromosome of maternal origin. Many cancers are associated with loss of a particular chromosome derived from a particular parent—usually the mother. The DNA of some genes is modified during the formation of gametes so as to have altered expression and be activated or inactivated.
Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005
genomic imprintingthe process whereby certain genes are modified (principally by METHYLATION) during GAMETOGENESIS, resulting in differential expression of parental alleles depending on whether of maternal or paternal origin. The ‘imprinted’ regions of the DNA are generally less active in transcription. Offspring normally inherit one maternal and one paternal copy of their genes, and generally both copies are active. However, expression of certain genes occurs from only one of the two copies, as a result of imprinting of either the maternal or paternal ALLELE at a particular LOCUS. The phenomenon can occur in a variety of organisms. Only a few human genes are imprinted and they tend to be clustered in the genome. Imprinting may have no effect on health and development, but in some cases can cause medical disorders such as Prader-Willi Syndrome and Angelman Syndrome. See also UNIPARENTAL DISOMY.
Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005