ADAMTS13 and congenital thrombotic thrombocytopenic purpura: Thrombotic thrombocytopenic (TTP) is a rare and life-threatening disorder characterized by microangiopathic hemolytic anemia with thrombocytopenia, fever, renal changes, and neurological symptoms.[1,2] While the pathogenesis of TTP is not understood yet, a deficiency of von Willebrand factor (VWF) cleaving protein, also known as a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13–VWF cleaving protein (ADAMTS13) causes TTP.[3,4] Congenital TTP is caused by an inherited deficiency of ADAMTS13 and acquired TTP is caused by autoantibodies against ADAMTS13.