A somatic epitype is a non-heritable
epigenetic
In biology, epigenetics is the study of stable phenotypic changes (known as ''marks'') that do not involve alterations in the DNA sequence. The Greek prefix '' epi-'' ( "over, outside of, around") in ''epigenetics'' implies features that are "o ...
alteration in a gene. It is similar to conventional epigenetics in that it does not involve changes in the
DNA primary sequence. Physically, the somatic epitype corresponds to changes in DNA
methylation
In the chemical sciences, methylation denotes the addition of a methyl group on a substrate, or the substitution of an atom (or group) by a methyl group. Methylation is a form of alkylation, with a methyl group replacing a hydrogen atom. These t ...
, oxidative damage (replacement of
GTP with oxo-8-dGTP), or changes in DNA-
chromatin
Chromatin is a complex of DNA and protein found in eukaryotic cells. The primary function is to package long DNA molecules into more compact, denser structures. This prevents the strands from becoming tangled and also plays important roles in r ...
structure that are not reversed by normal cellular or nuclear repair mechanisms. Somatic epitypes alter gene expression levels without altering the amino acid sequence of the expressed protein. Current research suggests that somatic epitypes can be altered both before and after birth, and this alteration can be in response to exposure to heavy metals (such as
lead
Lead is a chemical element with the symbol Pb (from the Latin ) and atomic number 82. It is a heavy metal that is denser than most common materials. Lead is soft and malleable, and also has a relatively low melting point. When freshly cu ...
), differences in maternal care, or nutritional or behavioral stress. There is no indication that somatic epitypes are heritable in a conventional epigenetic fashion. Some research suggests that methylation levels (and gene expression) can be reversed for some somatic epitypes by alterations in environmental factors such as diet.
See also
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Epigenetics
In biology, epigenetics is the study of stable phenotypic changes (known as ''marks'') that do not involve alterations in the DNA sequence. The Greek prefix '' epi-'' ( "over, outside of, around") in ''epigenetics'' implies features that are "o ...
Sources
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DNA
Epigenetics
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