TTP is associated with an autoimmune attack on which enzyme?

TTP is associated with an autoimmune attack on which enzyme?

• A. ADAMTS13
• B. Factor IX
• C. Von Willebrand factor
• D. Thrombin

Answer: (A)

TTP occurs when autoantibodies attack a specific enzyme in the circulation that normally regulates von Willebrand factor activity. That enzyme is ADAMTS13, a metalloprotease that cleaves ultra-large von Willebrand factor multimers into smaller, less active forms. When ADAMTS13 activity is markedly reduced by autoantibodies, ultra-large VWF multimers accumulate, promoting aggressive platelet adhesion and aggregation in small vessels. This leads to widespread microthrombi, causing thrombocytopenia, microangiopathic hemolytic anemia, and potential organ ischemia. Factor IX is a coagulation factor in the cascade, not the target of autoantibodies in TTP. Von Willebrand factor itself is the substrate that accumulates when ADAMTS13 is deficient, not the enzyme that's attacked. Thrombin is a central coagulation protease, not the autoimmune target in this condition.

TTP occurs when autoantibodies attack a specific enzyme in the circulation that normally regulates von Willebrand factor activity. That enzyme is ADAMTS13, a metalloprotease that cleaves ultra-large von Willebrand factor multimers into smaller, less active forms. When ADAMTS13 activity is markedly reduced by autoantibodies, ultra-large VWF multimers accumulate, promoting aggressive platelet adhesion and aggregation in small vessels. This leads to widespread microthrombi, causing thrombocytopenia, microangiopathic hemolytic anemia, and potential organ ischemia.

Factor IX is a coagulation factor in the cascade, not the target of autoantibodies in TTP. Von Willebrand factor itself is the substrate that accumulates when ADAMTS13 is deficient, not the enzyme that's attacked. Thrombin is a central coagulation protease, not the autoimmune target in this condition.