IDH1 and cancer: Querying four publicly available datasets (from Broad, the International Cancer Genome Consortium (ICGC), the Pediatric Cancer Genome Project (PCGP) and SickKids using cBioPortal [30, 31]) showed only three out of 300 patients had putative driving mutations in any of the TET enzymes (truncating mutations of TET1 or TET2) or missense mutation of IDH1 genes, indicating that genetic alterations are not the cause of loss of 5hmC in most cases (Additional file 1: Fig. S1d).