However, these genes had higher methylation levels in tumor tissues, including COL6A1 in KIRC, HNSC, THCA, KIRP, and COAD; COL6A2 in KIRC, LUSC, and BRCA; COL6A3 in LIHC and KIRC (Fig. 5A). Here, COL6A1 is linked to neoplasm.