Background Thrombotic microangiopathies are characterized by vascular microthromboses, microangiopathic hemolytic anemia, and thrombocytopenia. Although recent research has elucidated the pathogenesis of these rare thrombotic disorders to some extent, the determinants contributing to the onset and modulating the severity are largely unknown. It is likely that risk factors of venous and arterial thrombosis also play a role in this clinical setting.

Patients and Methods In the present study, we used a case-control and a case-only design, enrolling 23 patients (mean age [± SD] 35 ± 11 years) with a history of thrombotic microangiopathy and 689 control subjects to assess the role of gene polymorphisms of the thrombin-activatable fibrinolysis inhibitor (TAFI).

Results The prevalence of the TAFI decreasing G/G genotype of the C1542G polymorphism was significantly higher in patients compared to controls (odds ratio 3.88; 95 % CI 1.07 – 11.47; p=0.02). In addition, in a case-only design the TAFI 1542 G allele was more prevalent in patients suffering from a severe course compared to those with a mild or moderate course (odds ratio 20; 95 % CI 1.85 – 216.17; p=0.009). By contrast, no such association was found for the TAFI G505A polymorphism.

Conclusions Our study shows an association of the TAFI decreasing 1542 G/G genotype with an increased risk for thrombotic microangiopathies and a more severe course. This finding might be explained by the role of TAFI as an inhibitor of local inflammatory processes.

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