RUNX1 and acute myeloid leukemia: Familial myelodysplastic syndromes (MDSs) and acute myeloid leukemia (AML), also known as hereditary myeloid malignancy syndromes (HMMSs), have been recognized phenotypically for more than a century, with the first molecular basis discovered in 1999 through the identification of germline RUNX1 mutations [1].