Genetic polymorphism of GSTM1 and antioxidant supplementation influence lung function in relation to ozone exposure in asthmatic children in Mexico City.
BACKGROUND
We recently reported that antioxidant supplementation with vitamins C and E mitigated ozone related decline in forced expiratory flow (FEF(25-75)) in 158 asthmatic children in an area with high ozone exposure in Mexico City.


METHODS
A study was undertaken to determine whether deletion of glutathione S-transferase M1 (GSTM1 null genotype), a gene involved in response to oxidative stress, influences ozone related decline in FEF(25-75) and the benefit of antioxidant supplementation.


RESULTS
GSTM1 null children receiving placebo had significant ozone related decrements in FEF(25-75) (percentage change per 50 ppb of ozone 2.9 (95% CI -5.2 to -0.6), p=0.01); GSTM1 positive children did not. Conversely, the effect of antioxidants was stronger in children with the GSTM1 null genotype.


CONCLUSIONS
Asthmatic children with a genetic deficiency of GSTM1 may be more susceptible to the deleterious effects of ozone on the small airways and might derive greater benefit from antioxidant supplementation.