We found that blast phase of PV was characterized by overt myelodysplasia (n = 51, 88%); moderate to severe myelofibrosis (33 of 45, 73%); an abnormal karyotype (n = 51, 88%) that was often complex karyotype (n = 42, 72%); and gene mutations involving TP53 (55%), TET2 (27%), and DNMT3A (25%).
We used genome-editing technology to disrupt the zebrafish Tet2 catalytic domain. tet2(m/m) (homozygous for the mutation) zebrafish exhibited normal embryonic and larval hematopoiesis but developed progressive clonal myelodysplasia as they aged, culminating in myelodysplastic syndromes (MDS) at 24 months of age, with dysplasia of myeloid progenitor cells and anemia with abnormal circulating erythrocytes.
Recent studies are shedding light on the molecular basis of myelodysplasia and how mutations and epimutations can induce and promote this neoplastic process through aberrant transcription factor function (RUNX1, ETV6, TP53), kinase signalling (FLT3, NRAS, KIT, CBL) and epigenetic deregulation (TET2, IDH1/2, DNMT3A, EZH2, ASXL1, SF3B1, U2AF1, SRSF2, ZRSR2).
Furthermore, concurrent depletion of Ezh2 and Tet2 established more advanced myelodysplasia and markedly accelerated the development of myelodysplastic disorders including both MDS and MDS/MPN.
This retrospective study aims at evaluating the frequency and impact of TET2 mutations in 247 secondary acute myeloid leukemia cases referred to as myelodysplasia-related changes (n=201) or therapy-related (n=46) leukemias.
A new study reports common mutations in the TET2 gene in myelodysplasia and related myeloid malignancies, suggesting that TET2 has an important role in hematopoiesis and in the pathogenesis of this disease.