Figure 2.

Differentially methylated loci based on the interaction between maternal toenail Hg and urinary As. (A) Volcano plot for the relationship between the multiplicative interaction of log₂ toenail Hg and log₂ urinary As on DNA methylation at all 348,569 CpGs analyzed. Red and blue lines indicate −log₁₀(1 × 10⁻⁴) and −log₁₀(0.05) P-values, respectively. Colors: Yellow = CpG island, Black = CpG Shore, Blue=Shelfs and Open sea. Symbols: Circle = Infinium Type II, Square = Infinium Type I (B) Location of the top 100-CpGs on the basis of P-values compared to all CpGs on the methylation array. Among the top 100 CpGs with lowest P-value, there was a significant enrichment of CpG islands (P = 0.045) and S. Shore regions (P = 0.009).