Gene defect may raise passive smoke asthma risk 1/7/04. By Public Health Genetics Unit German scientists report that a genetic defect can increase a child's risk of developing asthma from second-hand smoke.

The rise in childhood asthma suggests that environmental factors, such as exposure to environmental tobacco smoke, play a role in the disease. However, there is increasing evidence that both genetic and environmental exposures play roles in determining an individual's susceptibility to the disease.

Recently, the glutathione S-transferase (GST) gene, one of a number of genes proposed to be involved in the detoxification of environmental tobacco smoke, has been suggested to modify the risk of childhood asthma in children. This finding builds on a body of evidence that suggests a role for GST in the detoxification of carcinogens in tobacco smoke.

Dr Michael Kabesch and colleagues at Children's University Hospital, Munich, determined the GST genotypes and exposure to environmental tobacco smoke (both in the uterus and after birth) in over 3000 German schoolchildren. The authors found that, among children with a specific GST genetic defect, children whose parents were smokers were at an increased risk of developing respiratory problems compared to those whose parents were non-smokers. The research was published in the journal Thorax.

The findings suggested that children with the genetic defect and whose parents smoked were approximately five and three times more likely to have current asthma or to have ever wheezed, respectively. Similar effects, although of a smaller magnitude, were also observed for a second genetic defect in the GST gene. Neither genetic defect appeared to have an effect on the development of asthma in children when exposure to environmental tobacco smoke was not included in the analysis.

PHGU comment

Both genetic and environmental factors play a role in determining an individual’s risk of developing a complex disease, such as asthma. The current research provides an indication that defects in the GST gene may increase the risk of respiratory problems in children exposed to environmental tobacco smoke.

However, despite the relatively large number of children in this study, the number possessing the genetic defect(s) and who were exposed to environmental tobacco smoke were relatively small. This, coupled with the small number of cases of respiratory problems in these individuals, requires a cautious interpretation of the findings. Deficiencies in GST, together with other genetic defects, may contribute to the adverse respiratory problems caused by exposure to environmental tobacco smoke and these should be studied further in larger numbers of individuals.

Article courtesy of the Public Health Genetics Unit .

Image credit: Anthea Sieveking

Further reading

Kabesch M, et al. Glutathione S transferase deficiency and passive smoking increase childhood asthma. Thorax. 2004 Jul;59(7):569-73. Abstract ; Full text