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What is the epigenome?

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DNA modifications that do not change the DNA sequence can affect gene activity. Chemical compounds that are added to single genes can regulate their activity; these modifications are known as epigenetic changes. The epigenome comprises all of the chemical compounds that have been added to the entirety of one’s DNA (genome) as a way to regulate the activity (expression) of all the genes within the genome. The chemical compounds of the epigenome are not part of the DNA sequence, but are on or attached to DNA (“epi-“ means above in Greek). Epigenomic modifications remain as cells divide and in some cases can be inherited through the generations. Environmental influences, such as a person’s diet and exposure to pollutants, can also impact the epigenome.

Epigenetic changes can help determine whether genes are turned on or off and can influence the production of proteins in certain cells, ensuring that only necessary proteins are produced. For example, proteins that promote bone growth are not produced in muscle cells. Patterns of epigenome modification vary among individuals, different tissues within an individual, and even different cells.

A common type of epigenomic modification is called methylation. Methylation involves attaching small molecules called methyl groups, each consisting of one carbon atom and three hydrogen atoms, to segments of DNA. When methyl groups are added to a particular gene, that gene is turned off or silenced, and no protein is produced from that gene.

Because errors in the epigenetic process, such as modifying the wrong gene or failing to add a compound to a gene, can lead to abnormal gene activity or inactivity, they can cause genetic disorders. Conditions including cancers, metabolic disorders, and degenerative disorders have all been found to be related to epigenetic errors.

Scientists continue to explore the relationship between the genome and the chemical compounds that modify it. In particular, they are studying what effect the modifications have on gene function, protein production, and human health.

For more information about the epigenome:

The National Institutes of Health (NIH) offers the NIH Roadmap Epigenomics ProjectThis link leads to a site outside Genetics Home Reference., which provides epigenome maps of a variety of cells to begin to assess the relationship between epigenomics and human disease.

The National Center for Biotechnology Information (NCBI) provides the NCBI EpigenomicsThis link leads to a site outside Genetics Home Reference. database of maps of the epigenomes of various species and many cell types.  

Human Epigenome AtlasThis link leads to a site outside Genetics Home Reference. from Baylor College of Medicine allows for comparison of the epigenomes of many species and cell types.  

Ongoing research is being done with the Human Epigenome ProjectThis link leads to a site outside Genetics Home Reference.

The University of Utah provides an interactive epigenetics tutorialThis link leads to a site outside Genetics Home Reference..

The National Human Genome Research Institute provides a fact sheetThis link leads to a site outside Genetics Home Reference. on Epigenomics.

Many tools for understanding epigenomics are available through the NIH Common Fund Epigenomics ProjectThis link leads to a site outside Genetics Home Reference..


Next: How do cells divide?

 
Published: September 29, 2014