For each of our patients, other confounding TMA syndromes, including Shiga toxin‐induced hemolytic uremic syndrome (HUS) and thrombotic thrombocytopenic purpura (TTP), were ruled out on the basis of negative Shiga toxin and normal ADAMTS13 activity, respectively. The gene discussed is ADAMTS13; the disease is thrombotic thrombocytopenic purpura.