Newsgroup: it.discussioni.misteri
Titolo: epigenetica: passi in avanti

Study of Holocaust survivors finds trauma passed on to children's genes
 
New finding is first example in humans of the theory of epigenetic 
inheritance: the idea that environmental factors can affect the genes 
of your children
 
Genetic changes stemming from the trauma suffered by Holocaust 
survivors are capable of being passed on to their children, the 
clearest sign yet that one person’s life experience can affect 
subsequent generations.
 
The conclusion from a research team at New York’s Mount Sinai hospital 
led by Rachel Yehuda stems from the genetic study of 32 Jewish men and 
women who had either been interned in a Nazi concentration camp, 
witnessed or experienced torture or who had had to hide during the 
second world war.
 
They also analysed the genes of their children, who are known to have 
increased likelihood of stress disorders, and compared the results with 
Jewish families who were living outside of Europe during the war. “The 
gene changes in the children could only be attributed to Holocaust 
exposure in the parents,” said Yehuda.
 
 
Holocaust survivors' grandchildren call for action over inherited 
trauma
 Read more
Her team’s work is the clearest example in humans of the transmission 
of trauma to a child via what is called “epigenetic inheritance” - the 
idea that environmental influences such as smoking, diet and stress can 
affect the genes of your children and possibly even grandchildren.
 
The idea is controversial, as scientific convention states that genes 
contained in DNA are the only way to transmit biological information 
between generations. However, our genes are modified by the environment 
all the time, through chemical tags that attach themselves to our DNA, 
switching genes on and off. Recent studies suggest that some of these 
tags might somehow be passed through generations, meaning our 
environment could have and impact on our children’s health.
 
Other studies have proposed a more tentative connection between one 
generation’s experience and the next. For example, girls born to Dutch 
women who were pregnant during a severe famine at the end of the second 
world war had an above-average risk of developing schizophrenia. 
Likewise, another study has showed that men who smoked before puberty 
fathered heavier sons than those who smoked after.
 
The team were specifically interested in one region of a gene 
associated with the regulation of stress hormones, which is known to be 
affected by trauma. “It makes sense to look at this gene,” said Yehuda. 
“If there’s a transmitted effect of trauma, it would be in a 
stress-related gene that shapes the way we cope with our environment.”
 
They found epigenetic tags on the very same part of this gene in both 
the Holocaust survivors and their offspring, the same correlation was 
not found in any of the control group and their children.
 
Children in the Auschwitz-Birkenau concentration camp. Facebook Twitter 
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 Children in the Auschwitz-Birkenau concentration camp. Photograph: 
Imagno/Getty Images
Through further genetic analysis, the team ruled out the possibility 
that the epigenetic changes were a result of trauma that the children 
had experienced themselves.
 
“To our knowledge, this provides the first demonstration of 
transmission of pre-conception stress effects resulting in epigenetic 
changes in both the exposed parents and their offspring in humans,” 
said Yehuda, whose work was published in Biological Psychiatry.
 
It’s still not clear how these tags might be passed from parent to 
child. Genetic information in sperm and eggs is not supposed to be 
affected by the environment - any epigenetic tags on DNA had been 
thought to be wiped clean soon after fertilisation occurs.
 
However, research by Azim Surani at Cambridge University and 
colleagues, has recently shown that some epigenetic tags escape the 
cleaning process at fertilisation, slipping through the net. It’s not 
clear whether the gene changes found in the study would permanently 
affect the children’s health, nor do the results upend any of our 
theories of evolution.
 
Whether the gene in question is switched on or off could have a 
tremendous impact on how much stress hormone is made and how we cope 
with stress, said Yehuda. “It’s a lot to wrap our heads around. It’s 
certainly an opportunity to learn a lot of important things about how 
we adapt to our environment and how we might pass on environmental 
resilience.”
 
The impact of Holocaust survival on the next generation has been 
investigated for years - the challenge has been to show 
intergenerational effects are not just transmitted by social influences 
from the parents or regular genetic inheritance, said Marcus Pembrey, 
emeritus professor of paediatric genetics at University College London.
 
“Yehuda’s paper makes some useful progress. What we’re getting here is 
the very beginnings of a understanding of how one generation responds 
to the experiences of the previous generation. It’s fine-tuning the way 
your genes respond to the world.”
 
Can you inherit a memory of trauma?
Researchers have already shown that certain fears might be inherited 
through generations, at least in animals.
 
Scientists at Emory University in Atlanta trained male mice to fear the 
smell of cherry blossom by pairing the smell with a small electric 
shock. Eventually the mice shuddered at the smell even when it was 
delivered on its own.
 
Despite never having encountered the smell of cherry blossom, the 
offspring of these mice had the same fearful response to the smell - 
shuddering when they came in contact with it. So too did some of their 
own offspring.
 
On the other hand, offspring of mice that had been conditioned to fear 
another smell, or mice who’d had no such conditioning had no fear of 
cherry blossom.
 
The fearful mice produced sperm which had fewer epigenetic tags on the 
gene responsible for producing receptors that sense cherry blossom. The 
pups themselves had an increased number of cherry blossom smell 
receptors in their brain, although how this led to them associating the 
smell with fear is still a mystery.
 
http://www.theguardian.com/science/2015/aug/21/study-of-holocaust-survivors-finds-trauma-passed-on-to-childrens-genes?CMP=share_btn_fb
 
 
Mk
 
-- 
"That which can be asserted without evidence, can be dismissed without
evidence."
-- Christopher Hitchens (1949 - 2011)

 environment could have and impact on our childrenâ  s health.
 
Inquietante... in effetti, se il DNA che viene passato al momento del 
concepimento da parte del genitore e' quello che *in quel momento* ha 
determinati geni "on" o "off", ha senso pensare che ci sia in qualche modo  
l'influenza di determinati eventi.
 
Viene da pensare che forse i figli e' meglio farli quando si sta bene 
proprio :)