Child abuse leaves "molecular scars" in victims' DNA

Toronto: Victims of child abuse bear the imprint of trauma in their DNA, which is detectable years later and could be used as evidence in court, according to scientists.

The results, based on a comparison of chemical labels on the DNA of 34 adult men, have yet to be confirmed by larger studies, and researchers are unsure whether these labels, known as methylation, affect the health of the victims.

However, the difference in methylation between those who have been abused and those who have not done so might someday be a useful biomarker for investigators or courts in assessing allegations of child maltreatment. children.

"Methylation is starting to be viewed as a potentially useful tool in criminal investigations – for example, by providing investigators with the approximate age of a person who has left a sample of their DNA," said Michael Kobor. , professor at the British University. Columbia (UBC) in Canada.

"It is therefore conceivable that the correlations we found between methylation and child abuse provide a percentage of likelihood of abuse," Kobor said. Methylation acts as a "variator" on genes, affecting the degree of activation or not of a particular gene.

Scientists are increasingly interested in the activation and deactivation of genes, known as epigenetics, because they are supposed to be influenced by external forces – the environment of A person or his experiences of life.

The researchers decided to look for methylation in sperm, assuming that infantile stress could affect long-term physical health of the victims, but also on their offspring, as demonstrated in previous animal experiments.

They identified a group of men participating in a much larger, long-term health monitoring study, and asked them to donate their sperm. In detailed questionnaires that they had completed years ago, some of the men reported being abused.

The researchers found a distinct difference in methylation between victims and non-victims in 12 regions of the male genome. Scientists were struck by the degree of "gradation" in these twelve regions: Eight DNA regions were more than 10% different and one region had a difference of 29%.

The study, published in Translational Psychiatry, does not demonstrate the long-term physical consequences of child abuse, as it is still unclear how the methylation of these genetic regions affects a person's health. In addition, scientists do not know whether methylation patterns survive the complex process of fertilization and can therefore be transmitted to the person's children.

"When the sperm meets the egg, there is a huge amount of genetic rearrangement and most of the methylation is at least temporarily erased," said Andrea Roberts, a researcher at the Harvard School of Public Health TH Chan in the United States.

"But finding a molecular signature in sperm allows us at least to take a step forward in determining whether child abuse could affect the health of the offspring of the victim," Roberts said.

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