Can smoking cigarettes increase cleft lip risk?
That's what researchers at the University of Iowa concluded after conducting an international study to determine if some babies are predisposed to cleft lip and/or palate because of a genetic inability to detoxify cigarette smoke.
The study concluded that fetuses lacking both copies of a gene used to counteract the smoke and whose mothers smoke during pregnancy have an increased risk of developing the condition.
About one in every 600 U.S. babies is born with a cleft lip and/or palate, according to the study.
The study's results found that up to 60 percent of babies with Asian ancestry and 25 percent of babies of European ancestry lack both copies of the gene, which is called GSTT1.
The study's lead author, Jeff Murray, M.D., put the findings in perspective, "If a pregnant woman smokes 15 cigarettes or more per day and her fetus doesn't have working copies of the GSTT1, the chances of the fetus developing a cleft increase nearly 20 fold."
When the gene is missing, the study said, a baby is unable to remove the toxins that may be transferred across the placenta when the mother smokes.
The Iowa researchers and a team of researchers from Denmark assembled a list of 16 genes directly involved in cigarette smoke toxicity and tested whether variations might adversely affect a person's ability to break down the toxic products.
The teams used an existing database of 1,244 children with clefts as well as their parents and siblings to compile 5,000 DNA samples. The data they uncovered revealed that pregnant women who smoked and whose fetuses lacked the GSTT1 enzyme were much more likely to give birth to a baby with a cleft.
"When the chemicals in cigarette smoke challenge the normal development of these structures," Dr. Murray said, "fetuses that lack the gene are at a distinct disadvantage."
Please contact the ADA if you have questions about this article.© American Dental Association. All rights reserved. Reproduction or republication is strictly prohibited without the prior written permission from the American Dental Association.