TET2 and myelodysplastic syndrome: Moreover, loss-of-function mutations in TET2, which impair its catalytic activity, are often observed in patients with chronic myelomonocytic leukemia (CMML), myeloproliferative neoplasms (MPN), myelodysplastic syndrome (MDS), as well as B cell and T cell lymphomas (Asmar et al. 2013; Couronne et al. 2012; Delhommeau et al. 2009; Langemeijer et al. 2009).