Familial platelet disorder with predisposition to myeloid malignancy (FPDMM), sometimes referred to as Thrombocytopenia 2, was first described in 1985 and molecularly characterized in 1999 as the result of pathogenic variants in the transcription factor RUNX1 (4). The gene discussed is RUNX1; the disease is hereditary thrombocytopenia and hematological cancer predisposition syndrome associated with RUNX1.