The facts that LMO2 is involved in lymphocyte differentiation and proliferation (Natkunam et al., 2007; Ryan et al., 2008), IL10 is involved in immune regulatory functions (Hedrich et al., 2010), and GSTM1 polymorphism is involved in tobacco-associated asthma (Gilliland et al., 2002; Wu et al., 2014), suggesting prenatal exposure of PTS could influence CG methylation in a series of genes involved in lymphocyte differentiation, immune regulation, and redox reaction. This evidence concerns the gene IL10 and asthma.