The rare and life-threatening disease thrombotic thrombocytopenic purpura (TTP) is caused by a severe deficiency in the metalloprotease ADAMTS13 (adisintegrinandmetalloprotease withthrombospondin type 1 motif, member 13).1ADAMTS13 is encoded by 29 exons which results in a multidomain protein containing a signal peptide, propeptide, metalloprotease domain, disintegrin-like domain, a first thrombospondin type 1 repeat (T1), cysteine-rich domain, spacer domain, seven additional T domains (T2-T8), and two CUB domains.2 This evidence concerns the gene ADAMTS13 and thrombotic thrombocytopenic purpura.