In CRC, multiple blood-based diagnostic methylation biomarkers have been studied, including ALX4, APC, HLTF, MGMT, NEUROG1, RASSF2A, Wif-1, FBN2, PI6, TMEFF1, SDC2, TAC1, THBD, and TFPI2 [96,102,103,104]. The gene discussed is SDC2; the disease is colorectal carcinoma.