Familial platelet disorder with propensity to myeloid malignancy is an autosomal dominant familial MDS/AML syndrome caused by inherited mutations in the hematopoietic transcription factor RUNX1. RUNX1 is located at 21q22 and causative mutations are most often frameshift, nonsense, or deletion mutations that result in premature protein truncation; missense mutations in the DNA binding domain are also reported. The gene discussed is RUNX1; the disease is myelodysplastic syndrome.