In addition, Bowatte et al. also first demonstrated effect modification by GSTT1 genetic variation, but not by GSTM1 or GSTP1 polymorphisms, on the association between traffic-related exposure and asthma in adults (77), in contrast to the study by Castro-Giner et al. that only detected an interaction with common polymorphisms in the NQO1 gene (78). Here, GSTP1 is linked to asthma.