NPM1 and acute myeloid leukemia: Again, although our IDH2 cohort was bigger and provided more statistical power, small patient numbers and underlying co-mutational patterns have to be considered when interpreting these data, although IDH2 R172 seems to define a distinct genetic AML subgroup, being mutually exclusive from class-defining genetic aberrations like NPM1 mutations as reported previously [6, 23, 49].