Figure 2

Comparison of the methylation levels in DNA from male smokers ( n = 64) and lifetime male nonsmokers ( n = 37) at the 146 probes covering the AHRR locus. The average of the nonsmokers is indicated by the red line, whereas the values for smokers when they diverge from that of the nonsmokers as illustrated by blue line. The location of those three AHRR probes with at least a trend for genome-wide significance is illustrated by the double asterisk. The exact ID, methylation values, and P values for the comparisons at each probe are given in Additional file 1: Table S1.