Oxidized form of 5-methylcytosine - 5-hydroxymethylcytosine: a new insight into the biological significance in the mammalian genome

The present review summarizes data on 5-hydroxymethylcytosine - a modification of cytosine with a recently discovered epigenetic effect. The biochemical mechanisms of 5-hydroxymethylcytosine formation and further modification in the mammalian genome are discussed; the role of 5-hydroxymethylcytosine in the epigenetic reprogramming during mammalian gametogenesis and early embryogenesis as well as in the regulation of gene expression is analyzed; data on the diseases and the adverse environmental factors, linked to the DNA hydroxymethyaltion disruptions is shown.