<h4>Background</h4>Immune-mediated thrombotic thrombocytopenic purpura (iTTP) is a rare, life-threatening thrombotic microangiopathy caused by severe <i>a disintegrin and metalloproteinase with thrombospondin motifs 13</i> (ADAMTS-13) deficiency due to autoantibodies. The gene discussed is ADAMTS13; the disease is thrombotic microangiopathy.