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Platelets: thrombotic thrombocytopenic purpura
James N George1, J Evan Sadler, Bernhard Lämmle
1Hematology-Oncology Section, Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City 73190, USA.
Hematology. American Society of Hematology. Education Program
|November 26, 2002
Summary
Thrombotic thrombocytopenic purpura (TTP) is linked to von Willebrand factor (VWF) abnormalities. A deficiency in the VWF-cleaving protease, ADAMTS13, causes TTP, with specific assays aiding diagnosis and management.
Area of Science:
- Hematology
- Molecular Biology
- Genetics
Background:
- Abnormalities in plasma von Willebrand factor (VWF) are associated with thrombotic thrombocytopenic purpura (TTP).
- Patients with chronic TTP exhibit larger-than-normal VWF multimers.
- A deficiency in the VWF-cleaving protease, ADAMTS13, is implicated in TTP pathogenesis.
Purpose of the Study:
- To review the structure, biosynthesis, and function of the ADAMTS13 protease.
- To describe mutations causing congenital TTP and the role of ADAMTS13 deficiency in both congenital and acquired TTP.
- To discuss assay methods for ADAMTS13 activity and their interpretation in diagnosing TTP.
Main Methods:
- Review of ADAMTS13 protease structure, biosynthesis, and function.
- Analysis of ADAMTS13 gene mutations in congenital TTP.
- Description of assay methods for measuring ADAMTS13 activity.
- Clinical evaluation and management strategies for TTP and HUS.
Main Results:
- Mutations in ADAMTS13 cause congenital TTP; autoantibodies against ADAMTS13 are linked to acquired TTP.
- Severe ADAMTS13 deficiency (<5%) appears specific for TTP but may not identify all cases.
- Clinical presentation and specific patient populations (e.g., pregnancy, drug-induced) influence TTP/HUS diagnosis and management.
Conclusions:
- ADAMTS13 deficiency is central to TTP development, with distinct genetic and autoimmune mechanisms.
- Accurate ADAMTS13 activity assays are crucial for TTP diagnosis, though sensitivity limitations exist.
- Tailored clinical approaches are necessary for managing TTP and HUS in diverse patient groups, considering factors like pregnancy, drug exposure, and autoimmune conditions.