RUNX1 and myeloproliferative disorder: RUNX1 (=AML1), located on chromosome 8q22, commonly involved in t(8;21)/RUNX1-RUNXT1 in AML, was shown to be also point mutated in patients with myeloid malignancies like AML, MDS and MPN with +21.55 A Japanese group found a poor prognostic impact of intragenic RUNX1 mutations in MDS but did not describe a correlation with +21.56