Male DNA found in female brains
Discovery suggests fetal cells can slip through blood-brain barrier
Children live on in their mothers’ brains for decades, and not just as memories. Scientists have found pockets of male DNA, presumably from boy fetuses, in the brain tissue of women who died in their 70s.
Not only is male DNA present in women’s brains, it’s common, researchers report online September 26 in PLOS ONE. J. Lee Nelson of the Fred Hutchinson Cancer Research Center in Seattle and her colleagues found snippets of a male-only gene in the brains of 18 of 26 women who died without neurological disease. The male DNA was spread throughout their brains.
The technique used in the study couldn’t distinguish if the DNA was from intact, functional brain cells, though in a separate test of brain tissue from a different woman, Nelson and colleagues did spot nuclei from male cells in the brain. Earlier studies in mice hinted that these foreign cells can integrate themselves into the brain and start functioning as nerve cells.
So far, cells from fetuses have turned up in women’s blood, livers, lungs, heart and other organs, so finding male DNA in the brain isn’t a complete shock, says geneticist Kirby Johnson of Tufts University in Medford, Mass., who wasn’t involved in the study. “From everything we knew, it’s not really that surprising.”What’s interesting is how the DNA could have gotten there. Male cells from a fetus could have broken through the blood-brain barrier — a wall that protects the fragile brain from pathogens in the blood. But that shouldn’t be possible, Johnson says.