FRIDAY, Dec. 16, 2005 (HealthDay News) -- Genetics may help determine which children will be most severely affected by secondhand smoke at home, a new study finds.
Researchers at the University of Southern California Keck School of Medicine studied 1,351 fourth-graders in southern California.
They found that a gene variant called "tumor necrosis factor 308A" increased a child's risk of respiratory-related school absences linked to secondhand smoke exposure.
Genetic tests showed that 24 percent of the students had one or more copies of this variant gene.
Children with at least one copy of the variant gene who lived in a home with two or more smokers had a four-fold increased risk of school absence due to lower respiratory illness, compared with children who also had at least one copy of the variant gene but weren't exposed to secondhand smoke.
The findings appear in the December issue of the American Journal of Respiratory and Critical Care Medicine.
The study authors noted that secondhand smoke increases the likelihood of school absences by boosting the risk for, and severity of, respiratory infection and by increasing asthma-related symptoms such as airflow obstruction and inflammation.
The American Lung Association has more about secondhand smoke.