MTHFR, Methylation and Histamine in Psychiatric Conditions
A diagram of the mechanism of DNA methylation. DNA methyltransferases attach methyl groups to the 5' position of cytosine nucleotides to methylate DNA. Reprinted by permission from Macmillan Publishers Ltd.: Nat. Rev. Neurol. 9, 35–43, copyright 2013.
A genetic change (mutation) is when the DNA sequence is altered. An epigenetic change alters the properties of the DNA/gene by the addition of a methyl group (Me) to the DNA but does not alter the sequence. The unmethylated and methylated DNA have identical sequence.