DIAPH1 and Macrothrombocytopenia: mDia1 KO mice had large platelets (P < .0001) with a small, but significant decrease in platelet number (P = .011) whilst DKO mice developed a more severe macrothrombocytopenia (37% reduction) with significantly decreased platelet number (P < .0001) and increased platelet volume (P < .0001).