Role of DNA methylation in personalized medicine

Epigenetics is the study of heritable variations in gene expression without changing in the DNA sequence. Epigenetic changes accurse during cell differentiation but continue during lifetime and could be influenced by several factors including age, environmental factors, lifestyle, and disease state. At least three systems including DNA methylation, histone modification and non-coding RNA are presently considered as epigenetic change. DNA methylation consider as a reversible procedure and a balance between DNA methylation and demethylation could be justify how epigenetic changes have vital role in a number of key processes including gene expression, genomic imprinting and when dysregulated, contributes to diseases like cancer. Changes in the expression of drug-response-related genes contributes significantly to inter-individual variances in drug response. Abnormal methylation and demethylation may also result in human diseases such as cancer, amentia, autoimmunity and diabetes. DNA methylation may happen in genes encoding drug metabolizing enzymes, drug transporters and drug targets, and can thereby alter the pharmacokinetics and pharmacodynamics of drugs. DNA methylation and demethylation can also affect drug responses by changing the expression of genes encoding drug metabolism enzymes, drug transporters and drug targets. Single nucleotide polymorphisms (SNPs) near DNA methylation sites can also function through affecting gene methylation and thus the expression of associated genes. Both these mechanisms can result in inter-individual difference in drug response. DNA methylation-related genetic variation is a progressively documented mechanism for altered drug-response and disease susceptibility. These new findings need integration into the practice of personalized medicine.