A second national questionnaire survey of TMA

Plasma ADAMTS13, von Willebrand Factor (VWF), and VWF Propeptide Profiles in Patients With Connective Tissue Diseases and Antiphospholipid Syndrome

Thrombotic thrombocytopenic purpura (TTP) frequently develops in patients with connective tissue diseases (CTDs). ADAMTS13 and von Willebrand factor (VWF) are closely related to the onset of TTP. We investigated the roles of ADAMTS13 and VWF in thrombotic events of patients with CTD. ADAMTS13 activity and VWF and VWF propeptide (VWFpp) levels in CTD, primary antiphospholipid antibody syndrome (pAPS), and controls were measured to examine their relationship with thrombosis. ADAMTS13 activity levels were significantly low in the patients with CTD but not in the patients with pAPS. No significant difference in the ADAMTS13 activity levels among the various CTD subgroups was found. The levels of VWF and VWFpp were significantly elevated in the patients with pAPS and CTD compared with that of control groups. Eleven patients with CTD developed TTP, and their ADAMTS13 activity levels were significantly lower than patients having CTD without TTP. However, the ADAMTS13 activity levels showed no difference between the patients having CTD with and without thrombotic events. The VWF antigen levels were significantly high in the patients having CTD with TTP. There were no significant differences in the VWF levels of the patients having CTD with TTP and thrombosis. The VWFpp levels were significantly high in the patients having CTD with TTP and thrombosis. The VWF and VWFpp levels were significantly high in the patients with pAPS. Decreased ADAMTS13 activity and elevated VWF and VWFpp levels were observed in patients with CTD. These abnormalities in patients with CTD may represent the increased risk of thrombosis in CTD.

Analysis of patients with atypical hemolytic uremic syndrome treated at the Mie University Hospital: concentration of C3 p.I1157T mutation

Atypical hemolytic uremic syndrome (aHUS) is caused by abnormalities of the complement system and has a significantly poor prognosis. The clinical phenotypes of 12 patients in nine families with aHUS with familial or recurrent onset and ADAMTS13 activity of ≥20 % treated at the Mie University Hospital were examined. In seven of the patients, the first episode of aHUS occurred during childhood and ten patients experienced a relapse. All patients had renal dysfunction and three had been treated with hemodialysis. Seven patients experienced probable triggering events including common cold, influenza, bacterial infection and/or vaccination for influenza. All patients had entered remission, and renal function was improved in 11 patients. DNA sequencing of six candidate genes, identified a C3 p.I1157T missense mutation in all eight patients in six families examined and this mutation was causative for aHUS. A causative mutation THBD p.D486Y was also identified in an aHUS patient. Four missense mutations, CFH p.V837I, p.Y1058H, p.V1060L and THBD p.R403K may predispose to aHUS manifestation; the remaining seven missense mutations were likely neutral. In conclusion, the clinical phenotypes of aHUS are various, and there are often trigger factors. The C3 p.I1157T mutation was identified as the causative mutation for aHUS in all patients examined, and may be geographically concentrated in or around the Mie prefecture in central Japan.

Elevated Von Willebrand factor propeptide for the diagnosis of thrombotic microangiopathy and for predicting a poor outcome

Thrombotic microangiopathy (TMA) is associated with vascular endothelial cell injury and is sometimes linked with poor outcome. Von Willebrand factor (VWF) propeptide (VWFpp) is considered to be a marker of vascular endothelial cell injury. The plasma levels of VWF, VWFpp, and thrombomodulin (TM) were evaluated for their use in the diagnosis of TMA in 75 patients with TMA. There were 30 TMA patients with marked decreases in ADAMTS13 (TMA/ADAMTS13) and 45 without the decrease (TMA/other). The plasma levels of TM, VWF, and VWFpp values were significantly high in patients with TMA, especially TMA/other group. The plasma levels of TM and VWFpp were significantly high in non-survivor with TMA. In the TMA/other group, the plasma levels of VWFpp were negatively correlated with ADAMTS13 activity. The plasma levels of TM correlated with the renal function, but the plasma levels of VWFpp did not. A ROC analysis indicated that VWFpp and TM were useful markers for the prediction of a poor outcome. These findings suggest that VWFpp is an useful marker for the diagnosis of TMA and for the prediction of poor outcome.