<b>Background:</b> Thrombotic thrombocytopenic purpura (TTP) is a life-threatening condition resulting from a disintegrin and metalloproteinase with thrombospondin type 1 motif, member 13 (ADAMTS13) deficiency, leading to the accumulation of ultra-large von Willebrand factor (vWF) multimers and widespread microvascular thrombosis. The gene discussed is ADAMTS13; the disease is deep vein thrombosis.