Study: Having a Male Child Leaves Male DNA in Women's Brains

More

The presence of the DNA persisted into old age and correlated with a slightly decreased risk of Alzheimer's disease. No word on behavior changes, but there's a joke in there about football or another hilarious but not-too-sensitive gender normative topic.

brainpregdnamain.jpg
DavidDuprey/AP

PROBLEM: We know of relationships between parity (bearing children) and likelihood of developing certain diseases later in life, but the mechanisms are unclear. Studies with mice had shown that DNA of a fetus can cross the blood-brain barrier and get into the brain (suggesting involvement in neurologic effects), but it hadn't been shown in humans. 

METHODOLOGY: Researchers out of the University of Alberta looked at autopsy specimens of the brains of 59 women (ages 32 to 101). They used PCR to scan the brain tissue for a gene that's only found on the male Y chromosome. The women's histories of pregnancy weren't available to the reseachers.

RESULTS: Male DNA was present in 63% of the female brains. It was distributed throughout the brain, not just in a particular area, and across all ages.

CONCLUSION: Male DNA is often found in the brains of women -- reasoned by the researchers to be a remnant from pregnancy with a male fetus -- and remains present into old age. That would mean fetal DNA is able to cross the blood-brain barrier, which hadn't been demonstrated before in humans.

IMPLICATIONS: Largely speculative at this point, but the researchers did look at how the presence and concentration of male DNA in the brain related to the women's likelihood of Alzheimer's Disease, and found it was slightly lower in the women who had the male DNA. But the sample size was small and there are a lot of other variables. The simple fact that the male DNA is there in the female brain, though, invites multiple directions for larger follow-up studies on neurocognitive diseases. If a fetus of a certain gender was found to have health benefits for the mother, it would also further complicate future discussions of sex selection and genetic engineering of our kids. 

The study, "Male Microchimerism in the Human Female Brain," was published yesterday in the online journal PLOS ONE.

Jump to comments
Presented by

James Hamblin, MD, is a senior editor at The AtlanticHe is the host of If Our Bodies Could Talk.

 
 
More

Get Today's Top Stories in Your Inbox (preview)

CrossFit Versus Yoga: Choose a Side

How a workout becomes a social identity


Join the Discussion

After you comment, click Post. If you’re not already logged in you will be asked to log in or register. blog comments powered by Disqus

Video

CrossFit Versus Yoga: Choose a Side

How a workout becomes a social identity

Video

Is Technology Making Us Better Storytellers?

The minds behind House of Cards and The Moth weigh in.

Video

A Short Film That Skewers Hollywood

A studio executive concocts an animated blockbuster. Who cares about the story?

Video

In Online Dating, Everyone's a Little Bit Racist

The co-founder of OKCupid shares findings from his analysis of millions of users' data.

Video

What Is a Sandwich?

We're overthinking sandwiches, so you don't have to.

Video

Let's Talk About Not Smoking

Why does smoking maintain its allure? James Hamblin seeks the wisdom of a cool person.

Writers

Up
Down

More in Health

Just In