Congenital thrombotic thrombocytopenic purpura caused by new compound heterozygous mutations of the ADAMTS 13 gene

Upshaw– S chulman syndrome ( USS ) is due to severe congenital deficiency of von W illebrand factor ( VWF )‐cleaving protease ADAMTS 13 (a disintegrin and metalloprotease with thrombospondin type 1 domains, nr 13) activity resulting in the presence of unusually large forms of VWF in the circulation, causing intravascular platelet clumping and thrombotic microangiopathy. Our patient, a 26‐year‐old man, had attacks of thrombotic thrombocytopenic purpura ( TTP ) with thrombocytopenia and a urine dipstick positive for hemoglobin (4+), often as the only sign of hemolytic activity. He had ADAMTS 13 activity of A ) leading to p.R1123H. This case report confirms the importance of the analysis of the ADAMTS 13 activity and its inhibitor in patients who have episodes of TTP , with a very low platelet count and sometimes without the classic biochemical signs of hemolysis.