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The environment to which we are exposed leaves its signature in our DNA

12 April 2016 Author: MolEpi - Molecular Epidemiology

The environment to which people are exposed during their lifetime leaves its mark in their DNA. This is the result of research by scientists of the Netherlands Twin Register (NTR) from the Vrije Universiteit Amsterdam (VU) in collaboration with researchers at Leiden University Medical Center (LUMC) and the Avera Institute for Human Genetics located in Sioux Falls, SD (USA). The researchers discovered associations between the environment and DNA modifications by analyzing information surrounding the DNA sequence -  the so-called epigenome - from monozygotic (identical) and dizygotic (fraternal) twins. The results have been published today in Nature Communications.

Differences between people in the epigenome
The expression of our DNA differs considerably between people. The sequence of the DNA code is different for every person, with the exception of monozygotic twins. In addition, there are switches in the genome that determine the expression of DNA sequence (the so-called epigenome). An important component of these switches is DNA methylation. The degree of DNA methylation differs between people even within monozygotic twin pairs. VU-researcher en first author of this study Jenny van Dongen: “One of the exciting findings from our study is that the degree of DNA methylation is regulated by the genome itself. So to some extent the genome regulates its own expression regardless of environment. And we now understand that the extent to which the genome regulates its expression differs markedly in different locations of the genome.”

The influence of the environment on the epigenome
Several studies have already suggested that exposure to cigarettes and secondary smoke, along with diet, can influence the level of methylation for certain genes. Van Dongen says, “This new research shows thousands of locations in the epigenome that are influenced by the environment. At these locations differences between people in the degree of methylation increase as they grow older. For instance, this applies to genes involved in cholesterol levels. Therefore, one of the important next questions is: What are the consequences for our health?”

The paper published today describes a catalog that includes over 400,000 locations of the epigenome. It also describes the extent to which DNA methylation levels differ between people at each location. For each location the catalog provides the impact of genes and environment. It also describes how the impact of genes and environment varies with age and how it varies between men and women. Age explains a larger amount of variation between people when compared to gender. The catalog will become a valuable resource that can be used by other researchers to examine the role DNA methylation plays in numerous diseases.

For more information please contact Jenny van Dongen