HP and congenital thrombotic thrombocytopenic purpura: The clinical spectrum of TTP can vary widely; however, the vast majority if not all patients will present with severe thrombocytopenia (platelet count <30 x10^9/L), evidence of microangiopathic hemolytic anemia (including schistocytes on peripheral smear, elevated LDH, indirect hyperbilirubinemia, low haptoglobin, and elevated plasma free hemoglobin) along with potential evidence of end organ damage.