Epigenetic modification of cytosines fine tunes the stability of i-motif DNA.

i-Motifs are widely used in nanotechnology, play a part in gene regulation and have been detected in human nuclei. As these structures are composed of cytosine, they are potential sites for epigenetic modification. In addition to 5-methyl- and 5-hydroxymethylcytosine modifications, recent evidence has suggested biological roles for 5-formylcytosine and 5-carboxylcytosine.