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	Child Abuse Leaves Genetic Mark: Study By Margaret Munro National Post February 23, 2009 http://www.nationalpost.com/news/story.html?id=1318494 Child abuse can indelibly mark and alter genes in its young victims, leaving them less able to cope with stress later in life, according to new Canadian research. A Montreal team has discovered large numbers of "chemical marks," which inhibit a key mechanism for dealing with stress, in the brains of young men who were physically or sexually abused as children and later committed suicide. "It's almost as if there is an imprint left," says Michael Meaney at McGill University, who heads the team that has already toppled many long-held views of how early experience impacts behaviour and genes. Their new study, published yesterday in Nature Neuroscience, is seen as the most convincing evidence yet that childhood abuse permanently modifies genes. "Here is a mechanism by which significant adverse experience becomes inscribed in our brains," says neuroscientist Dr. Steven Hyman, provost of Harvard University, who reviewed the paper for Nature. Not only has the Montreal group shown abuse can cause specific changes in the brain, but also a change in expression of an important gene, Dr. Hyman said in an interview. Abuse is believed to be prevalent, with as many as 10 to 15% of children physically or sexually abused, says Dr. Meaney. "It's tragic," he says. The new findings point to how insidious the impact can be. They also provide clues for better understanding the neurological impacts and devising treatments to reverse the damage, Dr. Meaney says. He has been making plenty of headlines lately. Last week one of his projects to identify Canadian children at risk of serious cognitive and behavioural disorders was held up as an example of the type of research Ottawa is no longer willing to fund. The work is, however, considered so important internationally that Dr. Meaney was asked to establish a similar program in Singapore, with almost eight times the $4-million he had received from the Canadian government, which did not renew the project last year. Dr. Meaney and his colleagues have long been intrigued with resiliency, and how genes and environmental factors interact. They specialize in "epigenetics" which explores how the genes we inherit from our parents are altered and turned on and off by exposures and experiences through life. "Obviously genes aren't everything," says Dr. Meaney, noting how identical twins often have very different lives. If one twin develops schizophrenia, he says, the chance the other twin developing the disorder is only 45% even though they have identical genes. He says the new study tries to tease out how one of life's most profound experiences -- the quality of parental care and family life -- can "literally affect the genome and its operation." It grew out of the Mc-Gill group's research which showed parental care in rats impacts not only behaviour but also the genes of their offspring. Baby rats that were licked more -- the rodent equivalent of hugs and good care -- grew up to be more assertive and confident than unlicked pups. The researchers showed that neglect altered an important stress regulation gene in the rat brain, a change that lasted into adulthood. They have now found a similar genetic change in men who were abused. They had suffered "major instances" of physical and sexual abuse as youngsters and committed suicide in their thirties. Working with brain tissues from the Quebec Suicide Brain Bank, the researchers looked at the DNA of the 12 men who committed suicide and had been abused in childhood, 12 men who died of suicide and were not abused, and 12 men who died accidentally. They looked for differences in chemical marks on a gene involved in stress response. Such marks are laid down early in life and are thought to be sensitive to one's environment. They punctuate DNA and program it to express genes at the appropriate time and place. The researchers found the men who had been abused as children had substantially more chemical marks, or flags, along the glucocorticoid receptor gene involved in the brain's stress response. The marks -- "methyl groups" containing carbon and hydrogen -- were three to four times more common on their genes. "It's quite significant," Dr. Meaney says. They have also shown excess marks impact the functioning of the gene, reducing the amount of protein produced in the brain's stress response pathway. This would have hampered the men's ability to cope with stress, and could have contributed to their suicides, Dr. Meaney says.
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