U of A study finds human brains can harbour foreign genetic material

Fragments of male DNA have been found in the brains of human females, according to a recent study coming out of the University of Alberta.

The study, Male Michrochimerism in the Female Human Brain, was recently published under the direction of lead author William Chan, a researcher in the U of A’s Department of Biochemistry.

“We looked into various regions of the brain of our subjects, and we found the foreign (male) DNA in many different places,” Chan explained. “For example, it’s not just stuck in the forebrain or the hindbrain — it seems to be scattered everywhere. We don’t know if there’s a reason for that yet. For now, we can only say that there seems to be a random distribution.”

Chan said the foreign DNA is also untranslated, meaning it serves no discernible function. However, he added that prior to his study, nothing was known about whether or not the human brain could actually harbour foreign genetic material.

“The brain is supposed to be a more important or privileged place — like your eye, for example,” he said. “You don’t want your immune system to go into your eye and mess around with it. That’s why we have a barrier around these privileged organs, (and) this made us wonder whether that would make it harder for foreign cells to get in there.”

Chan’s study focused on finding male DNA because it was the most straightforward method of determining foreign genetic material in the female brain.

“We could not use the same method to look for foreign female genetic material in a female, for example, because the method we used (in the paper) depended on looking for genetic material from the Y chromosome,” he said.

Chan added he and his team looked at the correlation between microchimerism and Alzheimer’s, revealing a plausible link between microchimerism and a lower rate of the disease.

“(But) you can’t just ask volunteers to give up a part of their brains for study,” he said.

“You basically have to (get samples) from cadavers. We hope that other people with better resources would be able to potentially look at our phenomenon and, one, reproduce it, (and) two, if they are interested in looking at the relationship between the phenomenon and human diseases, potentially do a larger study, look at the correlation, and see if they could find something that agrees with what we found.”

Chan said his research into microchimerism has come to an end, and future researchers will have to take things one step at a time.

“Without knowing whether the phenomenon occurs or not, we can’t ask about why it’s there. If we do find it’s there, the next step is to ask why … (but) for now, we don’t really have any evidence,” he said.

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