In spite of this, only few genes, including GALR2, ITGA4, NTRK2, OSMR, SFRP1, SFRP2, SLC16A12, TUBG2, MAL and NMDAR2A [8,14,21,22,36,41-43] (reviewed in [44] and [15]) have been found to harbor promoter methylation in more than 80% of colorectal cancers analyzed, and simultaneously in less than 10% of normal mucosa samples, opening up the possibility of achieving high sensitivities and specificities in a future test. The gene discussed is SFRP1; the disease is colorectal cancer.