Monday, January 21, 2013

Epigenetics: This is Why We Are So Vulnerable to Environmental Harms


Study Finds How Genes That Cause Illness Work Gina Kolata Jan 20 2013 New York Times http://www.nytimes.com/2013/01/21/health/study-pinpoints-what-activates-disease-causing-genes.html?nl=todaysheadlines&emc=edit_th_20130121&_r=0
[Excerpted] In the new study, researchers compared 354 newly diagnosed rheumatoid arthritis patients and 337 healthy people who served as controls. The goal was to review both groups’ white blood cells, examining their DNA for chemical tags — methyl groups — that could attach themselves to genes and turn them on or off. 
It was much more complicated than just studying genes themselves. Researchers know a gene will remain stable, but the chemical tags that turn the genes on and off are not so reliable. Their presence can be affected by the environment or medications or even the activity of other, distant genes. They can be a consequence of a disease or set off a disease....

Majia here: In this particular study the researchers found four chemical tags, out of hundreds, that seemed related to rheumatoid arthritis. These four tags were located in a group of genes controlling immune response. The tags were located in a gene known as C6orf10. That gene is not understood well.
 
Its important to emphasize that the operations of these chemical tags are subject to disruption. As the article states: "Their presence can be affected by the environment or medications or even the activity of other, distant genes. They can be a consequence of a disease or set off a disease...."

Nova provides a description of epigenetics:

[Excerpted] Once nurture seemed clearly distinct from nature. Now it appears that our diets and lifestyles can change the expression of our genes. How? By influencing a network of chemical switches within our cells collectively known as the epigenome. This new understanding may lead us to potent new medical therapies. http://www.pbs.org/wgbh/nova/body/epigenetics.html

Majia here: Its my belief that we will find the answers to autism and a variety of other conditions, especially immune and brain diseases - allergies, asthma, and parkinsons - in epigenetic processes.

This is exciting reseach and it illustrates the fundamental openness of biological systems to environmental inputs.

Failure to recognize this openness will be our biological undoing because we are rapidly changing our environment by creating and disseminating caustic chemicals and genotoxic radiation.

Here is the study and its abstract:

Epigenome-wide association data implicate DNA methylation as an intermediary of genetic risk in rheumatoid arthritis by Yun Liu et al Nature Biotechnology (2013) http://www.nature.com/nbt/journal/vaop/ncurrent/full/nbt.2487.html

[Abstract] Epigenetic mechanisms integrate genetic and environmental causes of disease, but comprehensive genome-wide analyses of epigenetic modifications have not yet demonstrated robust association with common diseases. Using Illumina HumanMethylation450 arrays on 354 anti-citrullinated protein antibody–associated rheumatoid arthritis cases and 337 controls, we identified two clusters within the major histocompatibility complex (MHC) region whose differential methylation potentially mediates genetic risk for rheumatoid arthritis. To reduce confounding factors that have hampered previous epigenome-wide studies, we corrected for cellular heterogeneity by estimating and adjusting for cell-type proportions in our blood-derived DNA samples and used mediation analysis to filter out associations likely to be a consequence of disease. Four CpGs also showed an association between genotype and variance of methylation. The associations for both clusters replicated at least one CpG (P < 0.01), with the rest showing suggestive association, in monocyte cell fractions in an independent cohort of 12 cases and 12 controls. Thus, DNA methylation is a potential mediator of genetic risk.

2 comments:

  1. Susceptibility to cancer is affected by genetic and epigenetic features, and is enhanced by ionizing radiation:

    http://link.springer.com/article/10.1007%2Fs00259-004-1731-6

    The damage to chromosomes and the genetic structure increases in each generation. Every generation is more susceptible to the effects of radiation than the previous one. Lower levels of radiation cause cancer and other diseases over time. The studies about radiation exposure and cancer become obsolete and invalid... the atomic bomb study is the most obsolete one.

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    1. Excellent find on the issue of increasing susceptibility across generations. I can use that cite. Thank you!!!

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