ABSTRACT
A family with a novel c.717_del frameshift and a c.3655C > T missense mutation of a disintegrin and metalloproteinase with thrombospondin type I motif, member 13 protein (ADAMTS13) is described. Family members have been under observation for 44 years. Two double heterozygotes have severe early-onset Upshaw-Schulman syndrome and require prophylactic plasma infusions. Analysis reveals that 2 weekly plasma infusions are not sufficient in preventing laboratory evidence of a thrombotic thrombocytopenic purpura (TTP) attack. Both the double heterozygotes also have a heterozygous factor V Leiden G1291A mutation. One underwent splenectomy, which did not reduce the frequency of TTP episodes but resulted in a recurrent pulmonary embolism and has necessitated lifelong anticoagulant therapy. The other has mild chronic renal failure and has had episodes of atrial fibrillation and cerebral infarction. Of the 3 heterozygotes in the family, 1 has had episodes of mild thrombocytopenia.