Epigenetic Variation in Humans


Epigenetic modifications alter the expression behaviour of genes without involving changes to the DNA (deoxyribonucleic acid) sequence itself. These modifications take a variety of forms, most notably DNA methylation and histone modification. Epigenetic differences allow alleles, cells or even individuals that are genetically identical to exhibit radically different phenotypes. Differentiation among cells underlies tissue differentiation and development. Differentiation between alleles within a cell is used to enhance clonal diversity, as in the immune system, and has been highjacked in the service of evolutionary genetic conflicts, as seen in the phenomenon of genomic imprinting. Epigenetic differences among individuals may account for some of the differences between monozygotic (identical) twins. Some recent studies have even suggested that these epigenetic mechanisms may allow organisms to adapt to environmental changes on very short timescales. Environmental adaptations could be epigenetically encoded and passed on to offspring, providing a potential mechanism for a neo‚ÄźLamarckian mode of evolution.

Keywords: DNA methylation; histone modification; genomic imprinting; epimutation


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Wilkins, Jon F(Jul 2008) Epigenetic Variation in Humans. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1002/9780470015902.a0020811]