AHRR and asthma: Self-reported maternal smoking was associated with a −1.5% (95% confidence interval (CI) = −2.4%, −0.6%) lower methylation at CpG locus cg05575921 on the AHRR gene; a 1% increase in DNA methylation at the same locus resulted in an odds ratio (OR) of 0.90 (95% CI = 0.83, 0.96) for the odds of asthma.