The Ghost in Your Genes

[Guest guest]

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. "

http://www.bbc.co.uk/sn/tvradio/programmes/horizon/ghostgenes.shtml