Optical detection of epigenetic marks: sensitive quantification and direct imaging of individual hydroxymethylcytosine bases.

Herein we report the specific labelling of the epigenetic modification 5-hydroxymethyl-cytosine along genomic DNA molecules with a fluorescent reporter molecule. Enzymatic glucosylation followed by a click chemistry reaction enables single molecule detection as well as global quantification of 5hmC in genomic DNA.