Long-term large-scale use of MA can cause adaptive changes in neurons through epigenetic mechanisms, leading to the occurrence of addiction behavior.[14,15] DNA methylation is an important epigenetic mechanism. DNA methylation prevents transcription factors from getting close to the gene promoter region, leading to inhibiting gene expressions and rendering a gene into a silent state. Abnormal methylation of CHN2 gene can lead to the expression changes of chimeric protein-2. This research studied the relationship between the methylation levels of CHN2 gene promoter for the first time. The results showed that the methylation levels of CHN2 gene promoter in MA addiction group were significantly higher than in the control group, the levels of non-methylation were significantly lower than in the control group. The findings supported the fact that the abnormal methylation of the CHN2 gene was associated with MA addiction. At present, the relationship between CHN2 gene and MA dependence has not been reported, but the relationship between CHN2 gene and substance dependence has been confirmed. Barrio-Real’s studies on smokers have shown that the polymorphism of the CHN2 gene was significantly correlated to nicotine dependence.[11]
