[Thrombotic thrombocytopenic purpura in children -- pathophysiologic mechanisms and their clinical significance].

Thrombotic thrombocytopenic purpura (TTP) is a severe occlusive microangiopathy characterized by thrombocytopenia, haemolytic anemia, renal dysfunction, neurological signs and fever. In most cases the disease is associated with the presence of ultra large multimers of von Willebrand factor in the serum due to defective function of the von Willebrand factor -- cleaving protease (VWF-CP). Mutations in the ADAMTS-13 gene cause markedly reduced or absent VWF-CP activity and they are detected in chronic relapsing and familial TTP. Autoantibodies inhibiting function of VWF-CP are detected in acquired idiopathic disease and in some secondary forms of TTP. TTP may be clinically undistinguishable from the atypical haemolytic uremic syndrome associated with complement factor H deficiency. Treatment and prevention methods differ according to the underlying cause and pathological mechanism of TTP. General availability of rapid and reliable assays of VWF-CP and its inhibitors is important for the optimalization of the therapy.