Evidence supporting multigenerational epigenetic inheritance continues to mount as a group of researchers discover that mothers who have a significant amount of lead present in their blood can epigenetically impact not only their unborn children, but their grandchildren as well. The study was published in Scientific Reports.
It is well known that children in the womb can be impacted by small amounts of exposure to lead. If a woman is pregnant and exposed to lead, it can harm the baby by passing through the placenta and into his or her developing organs and bones. In addition, women who have been exposed to lead in the past can pass it on and affect their unborn child’s brain formation, leading to developmental issues. Research conducted on this has found that an individual’s global DNA methylation profile can be affected by coming in contact with heavy metal toxicants. A global DNA methylation profile allows researchers insight into the total DNA methylation of a person’s genome.
The research team was headed by Dr. Douglas Ruden, professor from the Department of Obstetrics & Gynecology and the Institute of Environmental Health Sciences and director of epigenomics. He is also the program leader at the Center for Urban Responses to Environmental Stressors. The study was conducted at Wayne State and the results showed that a mother’s exposure to lead causes certain alterations in DNA methylation in their children and grandchildren. They detected these changes in dried blood samples of mothers and children from the Michigan Neonatal Bank. The DNA methylation changes were found to persist beyond the first generation.
Ruden indicates that, up until now, epigenetic impact of various environmental exposures have not been shown in humans beyond one generation. However, his team found that environmental toxins can cause epigenetic alterations in the blood of a newborn grandchild of a pregnant woman who was exposed to these toxins.
“Our results suggest that lead exposure during pregnancy affects the DNA methylation status of the fetal germ cells, which leads to altered DNA methylation in grandchildren’s neonatal dried blood spots,” explained Ruden. “This is the first demonstration that an environmental exposure in pregnant mothers can have an epigenetic effect on the DNA methylation pattern in the grandchildren.”
The researchers also indicate that this study might help pinpoint the genes that could be used as potential candidate biomarkers to advance transgenerational studies related to risk assessment.
Ruben noted that their pilot study offers indirect evidence that women who are exposed to lead during childbirth can impact the locus-specific DNA methylation status of their grandchildren. The changed DNA methylation status in the blood of the grandchildren, although, seemed to return to normal during postnatal development. When the fetal germline has been exposed to lead, according to Ruden, it can have a different epigenetic effect than when the child is exposed acutely.
Source: Sen, A., Heredia, N., Senut, M., Land, S., Hollocher, K., Lu, X., Dereski, M.O., Ruden. D.M. (2015). Multigenerational epigenetic inheritance in humans: DNA methylation changes associated with maternal exposure to lead can be transmitted to the grandchildren. Scientific Reports, 5: 14466.
Reference: Science Daily. Lead exposure in mothers can affect future generations. Science News. 2 Oct 2015. Web.