GSTP1 and asthma: The CAPPS study, which was particularly limited by sample size and did not have any homozygous minor allele carriers for GSTP1 rs1138272, reported a negative but not statistically significant association between NO2 and asthma at 7 years of age in children who were heterozygous for GSTP1 rs1138272 (OR = 0.76; 95% CI: 0.18–3.30 for a 7.2-μg/m3 increase in NO2; NTotal = 25) (Carlsten et al. 2011a).