Description
A core mechanism for epigenetic alterations of genomic DNA is hypermethyla-tion of CpG islands in specific genes and DNA hypomethylation, where methylation of CpG islands involves the course in which DNA methyltransferases (Dnmts) transfer a methyl group from S-adenosyl-L-methionine to the fifth carbon position of the cytosines. Region-specific DNA methylation is mainly found in 5"-CpG-3" dinucleotides within the promoters or in the first exon of genes, which is an important pathway for the repression of gene transcription in diseased cells. DNA hypomethylation is likely caused by methyl-deficiency due to variety of environmental influences. It has been demonstrated that alterations in DNA methylation are associated with many diseases, and especially with cancer