Epigenetics: Influence on Behavioral Disorders


Epigenetic modifications of the genome are critically important for normal functioning of a cell. In addition to DNA sequence variation, which has been the primary research target in human morbid biology, epigenetic dysregulation of genes may represent a fundamental mechanism of human diseases.

Keywords: epigenetics; neuropsychiatric disorders; Prader–Willi and Angelman syndromes; fragile X mental retardation; Rett syndrome; complex non‐Mendelian diseases; schizophrenia; DNA methylation; histone acetylation

Figure 1.

Unmethylated (left) and methylated (right) cytosines.

Figure 2.

Partial stability, or metastability, of epigenetic signals in cells during mitotic divisions. Methyl groups (squares) may be lost (top scenario) or de novo methylation may occur (bottom scenario), which results in different epigenotypes in cells with identical genotype, and which may lead to differential expression (wiggly lines represent mRNA molecules) of a homologous gene across the cells.

Figure 3.

DNA methylation and histone acetylation act in concert in epigenetic regulation of gene expression. (a) Histone acylation and low density of metC in the regulatory region of a gene correlate with high transcriptional activity of a gene. (b) Histone deacylation and high density of metC result in compact chromatin structure, which inhibits transcription (according to Robertson KD and Wolffe AP (2000) Nature Reviews Genetics 1: 11–19.)

Figure 4.

Epigenetic mechanism of discordance of monozygotic twins. Despite their identity in DNA sequences, monozygotic co‐twins exhibit epigenetic differences that result in differential expression of genes and differential susceptibility to a disease in genetically identical twins.



Gottesman I and Shields J (1982) Schizophrenia: The Epigenetic Puzzle. Cambridge, UK: Cambridge University Press.

Hagerman R (1998) Clinical and diagnostic aspects of fragile X syndrome. In: Wells R and Warren S (eds.) Genetic Instabilities and Hereditary Neurological Diseases, pp. 15–25. San Diego, CA: Academic Press.

Henikoff S and Matzke MA (1997) Exploring and explaining epigenetic effects. Trends in Genetics 13: 293–295.

Isles AR and Wilkinson LS (2000) Imprinted genes, cognition and behaviour. Trends in Cognitive Sciences 4: 309–318.

Jablonka E and Lamb M (1995) Epigenetic Inheritance and Evolution. Oxford: Oxford University Press.

Maynard Smith J (1990) Models of a dual inheritance system. Journal of Theoretical Biology 143: 41–53.

Morgan HD, Sutherland HG, Martin DI and Whitelaw E (1999) Epigenetic inheritance at the agouti locus in the mouse. Nature Genetics 23: 314–318.

Nicholls RD, Saitoh S and Horsthemke B (1998) Imprinting in Prader–Willi and Angelman syndromes. Trends in Genetics 14: 194–200.

Petronis A (2001) Human morbid genetics revisited: relevance of epigenetics. Trends in Genetics 17: 142–146.

Riggs A, Xiong Z, Wang L and JM L (1998) Methylation dynamics, epigenetic fidelity and X chromosome structure. In: Wolffe A (ed.) Epigenetics, pp. 214–227. Chichester, UK: John Wiley.

Van den Veyver IB and Zoghbi HY (2000) Methyl‐CpG‐binding protein 2 mutations in Rett syndrome. Current Opinion in Genetics and Development 10: 275–279.

Further Reading

Bestor TH (2000) The DNA methyltransferases of mammals. Human Molecular Genetics 9: 2395–2402.

Bird AP and Wolffe AP (1999) Methylation‐induced repression: belts, braces, and chromatin. Cell 99: 451–454.

Holliday R (1994) Epigenetics: an overview. Developmental Genetics 15: 453–457.

Jones PA and Takai D (2001) The role of DNA methylation in mammalian epigenetics. Science 293: 1068–1070.

Petronis A, Paterson AD and Kennedy JL (1999) Schizophrenia: an epigenetic puzzle? Schizophrenia Bulletin 25: 639–655.

Rakyan VK, Preis J, Morgan HD and Whitelaw E (2001) The marks, mechanisms and memory of epigenetic states in mammals. Biochemical Journal 356: 1–10.

Riggs A and Porter T (1996) Overview of epigenetic mechanisms. In: Russo VEA, Martienssen RA and Riggs AD (eds.) Epigenetic Mechanisms of Gene Regulation, pp. 29–45. Cold Spring Harbor: Cold Spring Harbor Laboratory Press.

Robertson KD and Wolffe AP (2000) DNA methylation in health and disease. Nature Reviews Genetics 1: 11–19.

Singal R and Ginder GD (1999) DNA methylation. Blood 93: 4059–4070.

Wolffe AP and Matzke MA (1999) Epigenetics: regulation through repression. Science 286: 481–486.

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How to Cite close
Petronis, Arturas(Jul 2006) Epigenetics: Influence on Behavioral Disorders. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1038/npg.els.0005234]