Epigenetics is the process of heritable change in gene activity despite alteration of the hosts DNA sequence, essentially causing a change in a phenotype without a change in the genotype of a host. To change the gene sequence without interfering with the DNA is accomplished by histone and DNA methylation. Gene silencing in DNA methylation is carried out by DNA methyltransferases 1, 2 and 3a/b (DNMT1, DNMT2, DNMT3A/B). On a broad level, DNMT’s methylate the fifth carbon of cytosine residues in DNA within CG dinucleotides.