Genetic predisposition increases childhood a...( Children who carry variations in spe...),Health

Children who carry variations in specific genes that metabolize vehicle emissions are more susceptible to developing asthma, particularly if they live near major roadways, a study led by researchers at the University of Southern California (USC) suggests.

Researchers found that children who carried variations in two genes and lived within 75 meters of a major road were up to nine times more likely to develop asthma than children who lived further away, says Muhammad T. Salam, Ph.D. candidate at the Keck School of Medicine of USC, and the studys lead author. The study will appear in the journal Thorax, and is now available online.

This is one of the first studies to report that children with certain genetic backgrounds are even more susceptible to asthma than if they lived near major roads and did not carry the variations, Salam says. We are working to understand how traffic-related exposures may interact with these genes, leading to asthma development.

Asthma is the most common chronic disease in children, and previous studies have shown that traffic-related pollution near the home increases asthma risk and reduces lung growth, according to USC experts.

Researchers drew upon data from the Childrens Health Study (CHS), a longitudinal study of respiratory health among school-age children in 12 Southern California communities. They compared associations between number of genetic variants and exposure to toxins among more than 3,000 study participants.

Researchers found that high levels of microsomal epoxide hydrolase (EPHX1)an enzyme that metabolizes polyaromatic hydrocarbons (PAH) in vehicle emissionswas associated with an increased risk for lifetime asthma. Children with high EPHX1 levels who also carried variations in glutathione S-transferase P1 (GSTP1) genes were four times more likely to have asthma.

Among children who lived within 75 meters of a major road, those with high EPHX1 activity were three times
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