Genetic faults may boost passive smoke asthma risk

Genetic defects can increase a child's risk of developing asthma from second-hand smoke, German scientists said on Thursday.

The defects they discovered involve an enzyme called glutathione S transferase (GST) which helps to detoxify the effects of passive smoking on the air passages.

"GST deficiency ... may add to the adverse health effects caused by passive and active smoking," said Dr Michael Kabesch, of the Children's University Hospital in Munich.

In a study of more than 3,000 German children published in the journal Thorax, Kabesch and his team studied defects in GST, the youngsters' respiratory health and the smoking habits of their parents.

Children with one defect whose parents were smokers were five times more likely to suffer from asthma and wheezing and had an even higher risk of shortness of breath than youngsters whose parents didn't smoke.

They also found that another fault with GST was linked with reduced lung function in children whose mothers smoked during pregnancy.

"Evidence exists that smoking during pregnancy affects the growth of the fetus and the maturation of the fetal lung, resulting in impairment of lung function in the newborn," Kabesch said.

The findings were reported a day after British researchers reported that passive smoking may be much more dangerous than scientists had previously thought.

High concentrations of a breakdown product of tobacco smoke in the body were associated with a 50-60 percent raised risk of coronary heart disease - about double the previous estimates.

SOURCE: Thorax, July 2004.