GRIA4 and colorectal carcinoma: Multiple methylation markers for (metastatic) CRC disease monitoring have already been described in literature, including ITGA4, MSC, EYA4, GRIA4, MAP3K14-AS1 [19], B4GALT1 [20], BCAT1, IKZF1 [21, 22], SEPT9, and SHOX2 [23, 24].