Although many of the genes represented in the assay have previously been reported as methylated in human cancers, most (33/42) of the candidate tumour suppressor genes that were methylated in ≥ 20% of all primary RCC tested had not previously been reported to be methylated in RCC (HTR1B, CALCA, IGFBP2, SOX17, COL1A2, BMP4, HS3ST2, FRZB, TAL1, MCM2, KCNK4, HOXC6, PITX2, SEPT5, IRF7, CCNA1, HOXA11, TERT, TMEFF2, EPHA3, PGF, MYOD1, MMP2, TNFRSF10C, PENK, EYA4, MYLK, IRAK3, ZNF215, SMARCB1, TWIST1, SCGB3A1, and IGFBP7). This evidence concerns the gene KCNK4 and renal cell carcinoma.