Epigenetics is the study of gene expression changes that result from processes that do not involve alteration of the DNA sequence. During embryogenesis, various epigenetic mechanisms play important roles in governing proper development, including chromatin remodeling and DNA methylation. Given that primary DNA sequences are not altered in a developing embryo, it is the epigenetic modifications that underlie the spatial and temporal control of gene expression. Hyper- and hypo-methylation of DNA can result in reduced and increased transcription of specific genes, respectively. Aberrant methylation patterns have been linked to the development and progression of a variety of cancers. Genomic imprinting is another epigenetic process that has been associated with human diseases, including Angelman Syndrome. Other epigenetic processes include histone acetylation and deacetylation, X chromosome inactivation, and heterochromatin regulation. While it is known that epigenetic changes can be maintained during cell division, evidence is mounting to support the notion that epigenetic marks can be transmitted from one generation to the next. Environmental factors such as stress and diet can have epigenetic consequences and these consequences may be passed on to offspring.
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