Study Confirms the Presence of Male DNA in the Brain of Women

Male DNA in the Brain of Women

A novel study from the Fred Hutchinson Cancer Research Center, in Seattle, USA, shows that the brains of women have traces of male DNA. According to the researchers, this could be linked to a previous pregnancy, having  a male fetus. Currently, the medical implications of this finding are unknown. However, precedent studies have shown that other kinds of microchimerism are related to different autoimmune diseases and several types of cancer. Microchimerism consists in the presence of a small number of cells that originate from another individual, thus being genetically different from the cells of the host. Microchimerism has been shown to have both positive and negative effects.

The study was published in the journal PLOS ONE, on the 26th of September. The lead author of the study is William Chan, from the Biochemistry Department from the University of Alberta. Chan worked with Dr Lee Nelson, an international authority in the field of microchimerism. Dr Nelson is the senior author of the published study.

According to the lead author, this is the first study to describe human male microchimerism in the brain of a human female. The findings of the research team show that it is possible for fetal cells to cross the human blood-brain barrier. This is the first study to support the idea that these fetal cells are capable of crossing the barrier in human subjects.

The brain autopsy of 59 women were analyzed by the research team. The subjects had died between the ages of 32 and 101. Almost 63% of the analyzed brains showed signs of microchimerism. These signs were spread throughout multiple brain regions. Scientists discovered signs of microchimerism in the brain of a woman who died at the age of 94, thus suggesting that this condition has the potential to persist a whole lifespan.

Microchimerism

 From the 59 women, 33 of them suffered from Alzheimer’s disease, whilst 26 of them had no neurological diseases. Scientists discovered that the brains of the females who were affected with Alzheimer’s had a smaller prevalence of microchimerism. However, they added that because the pregnancy history of the women was unknown, a link between the presence of microchimerism and Alzheimer’s disease could not be established.

“Currently, the biological significance of harboring male DNA and male cells in the human brain requires further investigation”, said Chan, whilst adding that this study doesn’t provide a link between the brain health of females and the presence of male microchimerism.

Notwithstanding, previous studies led by researchers from the Hutchinson Center have shown that male microchimerism is linked to the development of several autoimmune diseases and different types of cancer. For example, in breast cancer, scientists suggest that fetal cells can grant protection to the host. Despite their effect in breast cancer, fetal cells have been linked to an increased risk of colon cancer. Another study showed a link between fetal cells and a lower prevalence of rheumatoid arthritis for women who had already given birth, compared to women who hadn’t yet given birth to a child.