GSTP1 and asthma: A functional sequence variant in GSTP1 at codon 105 (Ile105Val) has been associated with asthma and susceptibility to the adverse effects of tobacco smoke and ambient air pollution in several studies (Aynacioglu et al. 2004; Ercan et al. 2006; Fryer et al. 2000; Gilliland et al. 2002a, 2004; Hemmingsen et al. 2001; Lee et al. 2004, 2005; Mapp et al. 2002; Palmer et al. 2006; Spiteri et al. 2000; Tamer et al. 2004).