As shown in Figures 2 and 4, the mean (sd) methylation levels of the CHN2 gene promoter in the case group were significantly higher than in the control group, which were 2795.55 (733.19) and 1026.73 (698.73), respectively, showing significant differences between the two groups (t=21.25, p<0.001). As shown in Figure 2, the mean (sd) non-methylation levels of the CHN2 gene in case group were 1165.56 (814.26), whereas the mean (sd) non-methylation levels were 4872.42 (1089.83) in control group, showing significant differences between the two groups (t=26.52, p<0.001). Pearson analysis showed no significant correlation between the methylation levels of CHN2 promoter and other factors (the age of initial MA use, the duration of MA use, combination with K powder, tobacco and alcohol) with p>0.05.
