5-Hydroxymethylcytosine

Patent Granted 5-Hydroxymethylcytosine is a DNA pyrimidine nitrogen base. It is formed from the DNA base cytosine by adding a methyl group and then a hydroxy group. It is important in epigenetics, because the hydroxymethyl group on the cytosine can possibly switch a gene on and off. It was first seen in bacteriophages in 1952.[1][2] However, in 2009 it was found to be abundant in human and mouse brains,[3] as well as in embryonic stem cells.[4] In mammals, it can be generated by oxidation of 5-methylcytosine, a reaction mediated by the Tet family of enzymes. Its molecular formula is C5H7N3O2.