IDH1 and acute myeloid leukemia: Class 3 (17%, n = 95) was characterized by mutations occurring in de novo AML such as NPM1 (67%, n = 64), DNMT3A (48%, n = 46), FLT3-ITD (35%, n = 33), IDH1 (21%, n = 20), and IDH2R140 (19%, n = 18), with virtually no chromosome abnormalities.