When TTP is suspected, emergent laboratory testing should include complete blood count (CBC), reticulocyte panel, serum haptoglobin level, serum lactate dehydrogenase level, direct antiglobulin test, indirect bilirubin, serum creatinine, blood smear evaluation for schistocytes, coagulation studies including prothrombin time, activated partial thromboplastin time, serum fibrinogen level, and an ADAMTS13 activity and inhibitor level. The gene discussed is ADAMTS13; the disease is thrombotic thrombocytopenic purpura.