Background: Factor XIII deficiency is an extremely rare, autosomal recessive coagulation disorder with estimated prevalence of 1/2000000 worldwide. This disorder represents with different clinical manifestations including, umbilical cord bleeding, recurrent abortion and CNS bleeding. CNS bleeding is a common but life threating complication of disease. The aim of this study was to evaluate the effect of a common polymorphism of thrombin activatable fibrinolysis inhibitor (TAFI) occurrence of CNS bleeding in patients with severe factor XIII deficiency.

Materials and Methods: This case control study was performed on 34 patients with factor XIII deficiency and history of CNS bleeding and 36 patients with factor XIII deficiency but without CNS bleeding as control group. Initially all patients were molecularly analyzed for factor XIII deficiency, then both groups were assessed for common TAFI Thr325Ile polymorphism. Finally obtained data was analyzed by SPSS software.

Results: Molecular analysis of TAFI Thr325Ile polymorphism revealed that almost all patients with CNS bleeding (89%) had this mutation that in 67% of patients was homozygote. There is a significant relationship between Thr325Ile polymorphism in homozygote manner with incidence of CNS bleeding in factor XIII deficient (OR 18.9, 95% CI 3.8 to 95.1).

Conclusion: It seems that Thr325Ile polymorphism is a suitable prognostic factor in patients with severe factor XIII deficiency and this probably polymorphism increases risk of CNS bleeding about 20 fold.