When Pregnant Mom Smokes, Baby's DNA May
WEDNESDAY, May 18 (HealthDay News) -- Women who smoke during
pregnancy may be putting their unborn children at increased risk
for a DNA change, a new study suggests.
The change, called DNA methylation, can change a gene's usual
function. The researchers argue that the altered genes, which can
be passed from parent to child, may explain why some children are
more likely than others to develop certain diseases, such as
The study, which was to be presented Wednesday at an American
Thoracic Society conference in Denver, analyzed questionnaires
completed by the mothers and grandmothers of 173 children that
assessed their smoking habits during pregnancy. DNA samples from
cheek cells of mothers and children were also collected and
The researchers found that DNA methylation of the AXL gene, a
gene that plays an important role in many human cancers and immune
response, occurred more than twice as often in children whose
mothers had smoked while carrying them in the womb.
They noted a stronger association in girls than in boys, and
they found no significant tie between a grandmother's smoking and
DNA methylation of AXL in either the mother or her child.
"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," study author Carrie Breton, an assistant professor of preventive medicine at the University of Southern California said in a American Thoracic Society news release. "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."
Investigating the effects of environmental exposures on
epigenetics, or changes in gene function or expression that occur
as the result of mechanisms other than changes to the underlying
DNA sequence, is a largely unexplored area of research that holds
great promise for understanding the biological mechanisms that
underlie exposure-disease associations, Breton added.
"We are interested in further characterizing the pattern of epigenetic marks across this gene and whether there is a widespread response to both maternal smoking exposure and air pollution exposure in utero," she said. "We hope to also evaluate timing of effects of exposure during trimester by increasing the number of samples we evaluated in a manner that will let us compare trimester-specific exposures."
Experts note that research presented at meetings should be
considered preliminary because it has not been subjected to the
rigorous scrutiny given to research published in medical
The U.S. Centers for Disease Control and Prevention has more on
smoking and pregnancy.
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