PTBP1 and hereditary thrombocytopenia and hematological cancer predisposition syndrome associated with RUNX1: To ascertain protein domains responsible for the interaction between RUNX1 and PTBP1, we used expression constructs with full length, wild type (WT) FLAG tagged RUNX1, and a series of point and deletion mutations found in patients with Familial Platelet Disorder with Associated Myeloid Malignancy (FPDMM) (Fig. 2A) [28–30, 42].