produce 5-hydroxymethylcytosine (hmC) (13). The hydroxymethyl mark itself is stable and exists
in relatively elevated levels in the brain; however, it is also the first step in active demethylation,
and either over-oxidation by the Tet family of proteins to aldehyde or carboxylate products or
deamination mechanisms followed by base excision repair then erases cytosine alkylation (14, 15).