Conversely, a tumour suppressor function seems likely for TET2, based on many reports of homozygous null mutations and chromosomal deletions involving the TET2 locus in myelodysplastic syndromes (MDS), myeloproliferative disorders (MPD) and frank myeloid malignancies ([22]–[27] ; reviewed in [28], [29]). This evidence concerns the gene TET2 and myeloproliferative disorder.