Thursday, December 23, 2010

Week 9 : Let's impress people with Epigenetics !

One cannot but notice that people are more and more concerned about their well-being and their health. And, nowadays, everyone knows that health together with personality and look is the consequence of two different factors; the environment and  the genetic code.

It is interesting to notice that even if it depends only on those two factors, it is very difficult to explain the existence or the appearance of those different phenomena. Indeed we can hear that cancer is a genetic disease, so how can we explain the success of the book " Anticancer : A New Way Of Life " by David Servan-Schreiber which explain that some food can prevent the developement of cancer ? It turned out that about 90% of cancer cases have revealed to be partly caused by environmental factors although there is a genetic background.

This book is a bestseller ans has been sold all around the world

Not only it is complex but it can also be taboo to talk about it. For example, it is not rare to see members of a family suffering from a genetic disease, refusing to be informed if they inherited particular genes because they know how hard is it to live with the sword of Damocles hanging over the head.

Painting of the sword of Damocles by Richard Westall, 1812.
What would you prefer ? Would you like to know if you possess the gene that trigger the disease or not ?

The question " Is this phenomenon more due to the environment or the genome ? " has been asked regarding homosexuality. A lot of parents feel guilty about that and wonder what they did wrong ( for those who consider it to be wrong of course ) but most of the gays and lesbians say that they are just born this way.

But, as you can imagine, some of the researches have been used improperly by political parties and religions, in particular in the U.S, to explain that homosexuality was a disorder that needed to be cured.

You may have heard about the law "Don't Ask Don't Tell" that is a good example of taboo.
To be in the news, President Obama signed the end of this law last Wednesday, the 22 of December 2010. 

It becomes highly sensitive when a politician talks about genetics. For example, in March 2007 President Nicolas Sarkozy said in Philosophie Magazine “ I am inclined to think that people are born pedophiles, and that it is also a problem that we do not know how to manage.” which has been vastly commented, in particular by the church and politic opponents. Maybe the taboo comes from the fear of a speech about genetic determinism, the negation of the free will or worst a possible echo of an eugenic policy. What is your opinion ? Are you shocked by this remark ?

In March 2007 Nicolas Sarkozy wasn't yet President of France but only a candidate.

According to eugenics one cannot marry anyone but only someone in the same classification.

 Eugenics used to brand individuals and then build up a hierarchy.

In the early decades of the 20th century eugenics was very popular.

Eugenics relied on a lot of sciences to spread its ideology.

What if it would be even more complex ?

The DNA contains the genetic information.

Well, the recent science of epigenetics added a new factor. Let be simple and schematic, the DNA sequence is a book that needs to be translated to be expressed, the fact is that the translator, RNA, will not translate the whole DNA sequence. That means that some genes are translated, and so expressed, and other not. But it is not static. Over time, the environment will trigger the expression of new genes and switch off others.

 Here is an example of what we can do in laboratory.
Two mice are fed differently, one will stay brown and healthy while the other become yellow and sick.
But the babies of the yellow one will stay yellow and sick even if they are fed normally.  

The traits acquire by epigenetics can be reversed. 

RNA transcription scheme

 For the non-scientific one just look at the two framed pictures.
You can see two different states, one is mostly like a line and so the information can be read.
The other one is much more compact, the DNA information is inaccessible, it's as if the book had stuck pages.

 For the chemists here you have the mechanism, called methylation and pretty much simple.

The thing is that the state of the genes, switched on or switched off is transmissible through generations ! Like a hereditary memory of the cells : you have to consider not only the environment and the genome but also the environment and the life of the ancestors !
Your genome keeps in memory the events of your life toghether with those of your parents, grand-parents ect ...

It turns out that women that have been raped give birth to children more prone to depression.

Children of survivors of the Nazi internment camp are much more stressed people.
Is it because they have been told awful story or is it an epigenetic phenomenon ?

A study revealed that women who lived 9-11 while they were pregnant gave birth to babies that synthesis more stress molecules whereas they were too young to be told stressful story.

A good example is the famine in Netherlands. It revealed a correlation between diabetes and famine, but not in people who suffered from the famine directly but in their children, years later. Like a transgenerational adaptation or a message to the next generation.

Dutch family

I invite you to watch this documentary called " The ghost of your genes" about the epigenetic including the example above and others.

Morality : We are taking more and more care about our well-being, with balanced food or by avoiding toxic environment like cigarettes and dangerous chemical products (they are not all dangerous) such as pesticides. But may be we should thing to avoid stressing event too, but I have to admit that it is more difficult to do. It would be, for sure, a good thing for us, but also for the children we don't have yet. It could be also a problem because we may feel more guilty regarding the issues of our children. Don't you think ?

Anticancer food.

Epigenetic is also something we should look at because it is one of the key to understand and potentially cure major diseases of our time such as diabetes, cancer and alzheimer.

 Japan is a developed country as Europe and the USA but their is much less cancer.  

 It has been proved that it is due to the consumption of green tea.
And because it involved an epigenetic aspect, a Japanese will still have less chance to develop some kind of cancer even if he doesn't drink green tea if his parents did.

Webography :


  1. Yes, indeed, I was shocked by Sarkozy's comments about pedophiles. I don't believe in the idea that one is born flawed. I realize that we have a genetic history to cope with, but I also think that the environment in which we evolve is a crucial factor in determining who we are going to be, though nothing is really determined once and for all as far as I'm concerned. Determinism is a dangerous concept which has been used in the past, as you suggested in this blog, to target populations, communities that were/are considered by some to be problematic because they tend to question normative behaviors/institutions. To be alive means to be in constant evolution as individuals and as communities--thus, nothing is ever ddetermined, fixed, written in stone--everything moves and science certainly is one of the prefered vortexes for that movement...

  2. That's a very interesting subject and i'm eager to know what we'll find out about it in the future. By the way, it's sad to see that even today some taboo subjects can curb scientific research !