[wordup] Epigenetics - The Ghost in Your Genes

[Adam Shand]

Via: : Brett Shand <brett at earthlight...>
Source: http://www.bbc.co.uk/sn/tvradio/programmes/horizon/ 
ghostgenes.shtml

The Ghost in Your Genes
The scientists who believe your genes are shaped in part by your  
ancestors' life experiences.

Biology stands on the brink of a shift in the understanding of  
inheritance. The discovery of epigenetics – hidden influences upon  
the genes – could affect every aspect of our lives.

At the heart of this new field is a simple but contentious idea –  
that genes have a 'memory'. That the lives of your grandparents – the  
air they breathed, the food they ate, even the things they saw – can  
directly affect you, decades later, despite your never experiencing  
these things yourself. And that what you do in your lifetime could in  
turn affect your grandchildren.

The conventional view is that DNA carries all our heritable  
information and that nothing an individual does in their lifetime  
will be biologically passed to their children. To many scientists,  
epigenetics amounts to a heresy, calling into question the accepted  
view of the DNA sequence – a cornerstone on which modern biology sits.

Epigenetics adds a whole new layer to genes beyond the DNA. It  
proposes a control system of 'switches' that turn genes on or off –  
and suggests that things people experience, like nutrition and  
stress, can control these switches and cause heritable effects in  
humans.

In a remote town in northern Sweden there is evidence for this  
radical idea. Lying in Överkalix's parish registries of births and  
deaths and its detailed harvest records is a secret that confounds  
traditional scientific thinking. Marcus Pembrey, a Professor of  
Clinical Genetics at the Institute of Child Health in London, in  
collaboration with Swedish researcher Lars Olov Bygren, has found  
evidence in these records of an environmental effect being passed  
down the generations. They have shown that a famine at critical times  
in the lives of the grandparents can affect the life expectancy of  
the grandchildren. This is the first evidence that an environmental  
effect can be inherited in humans.

In other independent groups around the world, the first hints that  
there is more to inheritance than just the genes are coming to light.  
The mechanism by which this extraordinary discovery can be explained  
is starting to be revealed.

Professor Wolf Reik, at the Babraham Institute in Cambridge, has  
spent years studying this hidden ghost world. He has found that  
merely manipulating mice embryos is enough to set off 'switches' that  
turn genes on or off.

For mothers like Stephanie Mullins, who had her first child by in  
vitro fertilisation, this has profound implications. It means it is  
possible that the IVF procedure caused her son Ciaran to be born with  
Beckwith-Wiedemann Syndrome – a rare disorder linked to abnormal gene  
expression. It has been shown that babies conceived by IVF have a  
three- to four-fold increased chance of developing this condition.

And Reik's work has gone further, showing that these switches  
themselves can be inherited. This means that a 'memory' of an event  
could be passed through generations. A simple environmental effect  
could switch genes on or off – and this change could be inherited.

His research has demonstrated that genes and the environment are not  
mutually exclusive but are inextricably intertwined, one affecting  
the other.

The idea that inheritance is not just about which genes you inherit  
but whether these are switched on or off is a whole new frontier in  
biology. It raises questions with huge implications, and means the  
search will be on to find what sort of environmental effects can  
affect these switches.

After the tragic events of September 11th 2001, Rachel Yehuda, a  
psychologist at the Mount Sinai School of Medicine in New York,  
studied the effects of stress on a group of women who were inside or  
near the World Trade Center and were pregnant at the time. Produced  
in conjunction with Jonathan Seckl, an Edinburgh doctor, her results  
suggest that stress effects can pass down generations. Meanwhile  
research at Washington State University points to toxic effects –  
like exposure to fungicides or pesticides – causing biological  
changes in rats that persist for at least four generations.

This work is at the forefront of a paradigm shift in scientific  
thinking. It will change the way the causes of disease are viewed, as  
well as the importance of lifestyles and family relationships. What  
people do no longer just affects themselves, but can determine the  
health of their children and grandchildren in decades to come. "We  
are," as Marcus Pembrey says, "all guardians of our genome."