Pyrograms of the LINE-1, MLH1 and MGMT methylation markers for different couples of frozen/FFPE DNA. Pyrograms of LINE-1 marker are those obtained for couple n° 10 (A and B) and for MLH1 and MGMT markers those for couples n°13 (C and D) and n°6 (E and F) respectively. Arrows indicate positions of internal controls of conversion, demonstrating no residual cytosines at the non-CpG sites. Gray areas indicate polymorphisms, between T/C, generated by bisulfite treatment. Level of methylation for a given CpG dinucleotide is reported above it (gray square).