IDH2 and myelodysplastic syndrome: Sequencing studies also confirmed that IDH activating mutations are frequent in clonal myeloid disorders and present in 5–20% of de novo normal karyotype acute myeloid leukemia (NK-AML) cases and in 10–20% of cases of secondary AML resulting from leukemic transformation of myelodysplastic syndrome (MDS) and myeloproliferative neoplasm (MPN) [107–112].