TET1 and myelodysplastic syndrome: For example, mutation or overexpression of DNMT1 drives colorectal cancer and non-small-cell lung cancer (NSCLC) (Zhang et al. 2020), whereas DNMT3A and TET2 mutations or TET1 translocations are linked with acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS) (Fig. 4; De Carvalho et al. 2010; Wu and Zhang 2011; Rasmussen and Helin 2016).