May 19, 2011

Smoking Moms May Affect Baby’s DNA

(Ivanhoe Newswire) --Children whose mothers and grandmothers smoked during pregnancy are more likely to suffer from childhood asthma and researchers may have just figured out why. A new study shows changes in a process called DNA methylation, that occurs before birth, may be a root cause.

DNA methylation can alter a gene's typical function, and the altered genes can be passed along from parent to child. For this study, researchers observed DNA methylation-related changes in the AXL gene in children exposed to maternal smoking in utero. This specific gene plays a major role in many human cancers and in immune response.

"We found that children exposed to maternal smoking in utero had a 2.3 percent increase in DNA methylation in AXL," Carrie Breton, ScD, assistant professor of preventive medicine at The Keck School of Medicine of the University of Southern California in Los Angeles was quoted as saying.

For the study, Dr. Breton and her team targeted the mothers and grandmothers of nearly 200 children participating in the Early Asthma Risk Factors Study. Using a detailed questionnaire, the researchers assessed their smoking habits during pregnancy. DNA samples collected from cheek cells of mothers and children were also evaluated. Researchers found that DNA methylation of AXL was associated with in utero exposure to maternal smoking. They also found that grand-maternal smoking was not significantly associated with AXL methylation in either the mother or the child.

"Environmental exposures occurring in utero have the potential to affect DNA methylation patterns before birth. Imprinted genes appear to be particularly susceptible to these exposures since they come from one parent and only a single copy from one chromosome in DNA is active," Dr. Breton was quoted as saying. "Any environmentally induced epigenetic changes will have greater impact on gene expression and function. In utero and early life exposures are likely to be important, given what we know about timing during development when epigenetic marks are established."

Dr. Breton concluded that investigating the effects of environmental exposures on epigenetics is a largely unexplored area of research, and could hold great promise for understanding biological mechanisms that underlie exposure-disease associations.

SOURCE: ATS 2011 International Conference, May 18, 2011