Our study suggests that FAP normal mucosa is more prone to acquire those CRC-associated methylation alterations, as 45% of all DMPs in FAP normal colon (when compared to LS normal colon) were similarly altered in at least one group of LS tumors, and 10% were altered in all LS tumor groups, always alike hyper- or hypomethylated (Additional Fig. 6; Additional Tables 2, 3). This evidence concerns the gene FAP and Leigh syndrome.