HRAS and neoplasm: Unsupervised hierarchical clustering with respect to the 10% most differentially methylated probes, as determined by standard deviation, revealed two clusters (Fig. 1, extended heatmap including normal samples in Supplemental Figure 1), from here on referred to as clusters A and B. Cluster A (n = 28) contained the majority of tumours with mutations in the RET, NF1 and HRAS genes and most of those without known mutations, whereas cluster B (n = 11) contained the majority of the tumours with mutations in the VHL gene.