Male DNA in the female brain?

Got a man on your mind? According to a new study published by the Public Library of Science One, male DNA has been found inside the human female brain for the first time.

The ground breaking study suggests that after a mother carries a son in her womb, or a sister shares a womb with her brother, she carries male fetal DNA in the far recesses of her brain for decades.

This would mean that the act of having a child is not the one-way transmission of the parents’ DNA to the child that we thought it to be, but at least to some degree, an exchange of DNA from mother and child. A woman, over the course of her life, would take on the DNA of the sons she bears, even those conceived and miscarried.

For the study, conducted by the Hutchinson Cancer Research Center and the University of Washington in Seattle, researchers examined the post-mortem brains of 59 women. Of these, they found that 63 per cent of the brains had a carrier fetal DNA that could have only come from a male.

Co-author of the study, rheumatologist J. Lee Nelson, said this “suggests we need a new paradigm of the biological self.” We are not simply the product of two biological parents and a genetic roll of the dice.

The male DNA was scattered throughout the brain but was found to be clustered in areas such as the hippocampus, which processes memories, and the parietal and temporal lobes of the brain’s prefrontal cortex, which handles perception, sensation, sensory integration and language comprehension.

Unexpectedly, researchers also found that the 33 women with Alzheimer’s disease had less male DNA in their brain than the 26 women without Alzheimer’s. It has long been known that Alzheimer’s is more prevalent in women than in men, suggesting that bearing a son could have a protective effect on the brain.

But these are, of course, very early days. There is a whole new world of research that needs to be done before any concrete statements can be made about how carrying a male fetus might influence a mother’s risk of developing Alzheimer’s disease or affect other brain functions — but in the meantime, the findings do pose intriguing questions on how we define ourselves biologically.

Sources: PLoS One, LA Times, The Indian Express, Canada.com, eScience News

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