TET2 and neoplasm: Using the χ2 test, consistent with TET2's main role being further oxidation of 5hmC, we saw a significantly greater frequency of SNVs/indels in Tet2−/− tumours at loci with 5hmC peak gains compared to loci with no change in 5hmC/5mC peaks and loci with 5hmC peak loss or 5mC peak gain (Fig. 4d,e and Supplementary Fig. 4b,c).