Conclusion
The individualized differences in drug response require more precise personalized strategies to achieve better clinical outcomes. Some individual factors account for these individual differences through affecting ADME gene expression. The expression of ADME gene is not only determined by the nucleotide sequence, but also affected by epigenetic. This review summarized the effects of individual factors on DNA methylation of ADME genes, and attempted to provide epigenetic insights in explaining individual differences in clinical treatment by combining DNA methylation of ADME gene and expression. There are six kinds of factors that are summarized: parental exposure, environmental pollutants exposure, obesity and diet, drugs, gender and others. Most studies reported significant methylation changes, but few mechanistic findings were reported. Many clinical studies included showed that such findings can be translated into clinical practice with clinical significance. The epigenetic mechanism underlying the effects of individual factors remained to be studied.