Effects of glutathione S-transferase M1, T1 and P1 on lung function in asthmatic families.

RATIONALE: Previous data have suggested that glutathione-S-transferase (GST) genotypes are important in determining the rate of lung function growth in childhood. This effect was most marked in Caucasian children with asthma.
OBJECTIVES: We investigated the association of lung function with GSTM1, GSTP1 and GSTT1 genotypes in Caucasian families with asthma.
METHODS: Four hundred and eighteen children and 316 parents from 224 Caucasian families were recruited via a child with asthma, the proband. Associations between lung function and GST genotype were determined using multilevel models.
RESULTS: There were no observed associations between lung function and GST genotype in parents. However, in the children, the GSTP1 val(105)/val(105) and GSTM1 null genotypes were associated with significantly higher forced expiratory volume in 1 s (FEV(1)) and FVC values as percentage of predicted. This effect was not statistically significant in the probands but was marked in their siblings in whom GSTP1 val(105)/val(105) was associated with 9.4% higher FEV(1) and 10.7% higher FVC (P=0.005 and 0.001, respectively). The GSTM1 null genotype was associated with a 6.7% higher FEV(1) and 4.1% higher FVC (P=0.003 and 0.063, respectively). These effects remained significant after correcting for the confounders of individual atopic status, tobacco smoke exposure and familial aggregation of lung function values.
CONCLUSIONS: GSTM1 and GSTP1 genotypes are important determinants of lung function in childhood. The smaller differences seen in probands are predicted by a simple model in which more rapid decline in lung function is seen in these individuals.