We were able to validate differential methylation in 15 DMRs, but it is possible that the low-level methylation that is observed in a small subset of the normal samples for several of the regions, e.g. HOXD10, HOXD3 and SIM1, is a result of the use of tissue, which have been exposed to the same environmental factors as the tumor tissue. Here, HOXD3 is linked to neoplasm.