Mutations in epigenetic regulators of DNA methylation TET methylcytosine dioxygenase 2 (TET2) and mixed-lineage leukaemia protein 3 (MLL3) were observed in ATLL patients, as well as CpG hypermethylation in gene encoding zinc finger transcription factors and major histocompatibility class I proteins (44, 45). Here, TET2 is linked to adult T-cell leukemia/lymphoma.