Epigenetic research plays an important role in the malignant tumor genotyping and tumor clinical treatment recently.Epigenetics is the study of changes in gene function that are mitotically and/or meiotically heritable and that do not entail a change in DNA sequence,including DNA methylation and histone modifications.DNA methylation is one of the most important epigenetic modifications often occurring on the cytosine of CpG islands located in gene promoter regions,which is thought to be closely correlated w...