ADAMTS13 and thrombotic thrombocytopenic purpura: ADAMTS13 deficiency is most frequently acquired via ADAMTS13 autoantibodies, but rarely, it is inherited via mutations of the ADAMTS13 gene.2 TTP could be secondary to infections (HIV-1, etc.), pregnancy, bone marrow transplantation, and medication use (anti-viral such as acyclovir, quinine, platelet aggregation inhibitors such as ticlopidine, clopidogrel, prasugrel).