Factor XIII levels and factor XIII B subunit polymorphisms in patients with venous thromboembolism.

Background: The association of plasma factor XIII (FXIII) level with venous thromboembolism (VTE) is still controversial and the effect of sex and FXIII B subunit (FXIII-B) polymorphisms in this respect have not been explored.

Objectives: 1/ To determine FXIII activity and antigen levels in patients with a history of VTE and how they are influenced by sex and FXIII-B polymorphisms. 2/ To explore the association of FXIII levels and FXIII-B polymorphisms with the risk of VTE.

Methods: 218 VTE patients and equal number of age and sex matched controls were enrolled in the study. FXIII activity was measured by ammonia release assay; FXIII-AB and FXIII-B levels were determined by ELISAs. FXIII-B polymorphisms were identified by RT-PCR using melting point analysis.

Results: Adjusted FXIII activity and FXIII-AB antigen levels were significantly higher in females with a history of VTE than in the respective controls. FXIII-B levels were significantly lower in male VTE patients than in controls. FXIII-AB antigen levels in the upper tertile increased the risk of VTE in females (adjusted OR: 2.52; CI: 1.18-5.38). Elevated FXIII-B antigen level had a protective effect only in males (adjusted OR: 0.19; CI: 0.08-0.46). FXIII-B Intron K c.1952+144 C>G polymorphism significantly lowered FXIII activity, FXIII-AB and FXIII-B antigen levels in both groups. FXIII-B polymorphisms did not influence the risk of VTE.

Conclusions: In VTE patients the changes of FXIII level and their effect on the risk of VTE show considerable sex-specific differences. Intron K polymorphism results in decreased FXIII levels, but does not influence the risk of VTE.