Research team to examine impact of genetics and exposure to secondhand smoke



(From left) Drs.Yanbin Dong, Martha Tingen and Haidong Zhu are part of the MCG research team that will study whether exposure to secondhand smoke increases the chance that children with...
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Whether exposure to secondhand smoke increases the chance that children with a family history of cardiovascular disease will develop the disease themselves is under study at the Medical College of Georgia.

If those children also have a variation in at least one of four genes responsible for metabolizing nicotine, their risk may increase even more because nicotine might stay in the body longer and do more damage, an interdisciplinary research team says.

Researchers will study 585 children age 15-20 who have a parent, grandparent or both with essential hypertension and/or a heart attack by age 55.

"What I hope to take away from this is more information for parents and caregivers to be able to share with them information about the risk of future disease that their behavior places on their child," says Dr. Martha Tingen, a nurse researcher at the Georgia Prevention Institute and principal investigator on the $220,000 National Institute of Nursing Research grant.

Researchers will look for adverse clinical cardiovascular measures, including reduced ability of arteries to dilate; the blood encountering increased resistance as it travels through vessels; higher blood pressure; and an increase in the size of the pumping chamber of the heart a result of pumping against elevated pressure.

Exposure to the damaging effects of nicotine and other pathogens in smoke may also cause a vicious cycle in the body.

"It likely causes damage to cells on the inner wall lining of blood vessels, which results in less adaptive capacity of the vessels and arteries, which may then cause greater strain on the heart," says Dr. Tingen.

Children exposed to secondhand smoke who have a variation of one or more of the genes that metabolize nicotine CYP1A1, GSTM1, GSTT1 and CYP2A6 can experience cellular damage because the nicotine does not leave the body as quickly, she says.

"And if that's happening, they're going to have more of these adverse pre-clinical cardiovascular measures that predispose them to developing cardiovascular disease," she says.

This research is particularly important because nearly 50 percent of people ages 17 and older are exposed to secondhand smoke in the workplace and each year in Georgia alone, 423,000 children are exposed to smoke at home. In the United States, 45,000-60,000 cardiovascular deaths each year are linked to non-smoker's exposure to secondhand smoke, Dr. Tingen says.

The first step will be to unfreeze the blood samples the children come from a 15-year longitudinal database kept by Dr. Frank Treiber, MCG vice president for research and a GPI child psychologist. Then Drs. Yanbin Dong and Haidong Zhu, MCG molecular geneticists, will perform the genotyping looking for children with variations in the identified genes. Dr. Gaston Kapuku, a GPI cardiologist, will help interpret the cardiovascular measures. The blood samples will then be sent to Advanced Bioanalytical Service Laboratories in London for analysis of cotinine levels, a metabolized version of nicotine and a reliable indicator of secondhand smoke exposure.

"If kids are exposed in the home and they have genetic alterations that make nicotine stay in the body longer, then there's an increased likelihood that they're at greater risk for developing cardiovascular disease," says Dr. Tingen.

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Last reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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