IDH1 and myelodysplastic syndrome: A further MDS category includes patients with mutations that are recurrently described in de novo acute myeloid leukemias (NPM1, FLT3, IDH1, and RUNX1); this category is associated with a high risk of disease progression and poor outcome, suggesting that the current threshold of 20% marrow blasts included in the current WHO classification of myeloid neoplasms might be not appropriate to recognize different biological distinct disease categories [41].