The magnitude of association between BC exposure and demethylation of IL4 CpG−48 and NOS2A CpG+5099 measured 5 days later appeared to be greater among seroatopic children, especially those sensitized to cockroach allergens (RR [95% CI] 0.55 [0.37–0.82] and 0.67 [0.45–0.98] for IL4 CpG−48 and NOS2A CpG+5099, respectively), compared to non-sensitized children (RR [95% CI] 0.87 [0.65–1.17] and 0.95 [0.69–1.33] for IL4 CpG−48 and NOS2A CpG+5099, respectively); however, the difference was not statistically different. The gene discussed is NOS2; the disease is breast cancer.