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%).
Contrarily, DNA methylation genes (DNMT3A, IDH1, IDH2 and TET2) were mutated most often in PV (0·5) and less frequently in ET (0·23) and PMF (0·20), but without reaching statistical significance.
Our previous study (unpublished data) showed that there was a high frequency distribution in rs3733609 C/T genotype at Ten-Eleven Translocation 2 (TET2) locus in one Chinese familial primary myelofibrosis.
These results show epigenetic differences between PMF and polycythemia vera/essential thrombocytosis and reveal methylomic signatures of ASXL1 and TET2 mutations.
We have studied the mutational status of TET2 (complete coding region), ASXL1 (exon12), IDH1 (R132), IDH2 (R140 and R172), and c-CBL (exons 8 and 9) in 62 MPN patients (52 essential thrombocythemia (ET), five polycythemia vera (PV), and five primary myelofibrosis (PMF)) negative for both JAK2 (V617F and exon 12) and MPL (exon 10) mutations.
In addition to the JAK2V617F mutation, different genetic markers have recently been discovered in PMF, the most relevant ones being the mutations in the thrombopoietin (MPL), TET2, and EZH2 genes.
TET2 mutations were mainly observed (10 of 12) in patients with primary myelofibrosis or patients with polycythemia vera or essential thrombocythemia who secondarily evolved toward myelofibrosis or acute myeloid leukemia.