GSTP1 and asthma: However, a recent study demonstrated that GSTP1 polymorphism significantly modified risk of wheeze in children with age 5 years who had prenatal exposure to APAP (Perzanowski et al., 2010), while an another study of APAP use versus childhood asthma incidence, maternal GSTT1 and GSTM1 but not GSTP1 genotypes were found to modify the risk of asthma incidence (Shaheen et al., 2010).