title: Factor XIII Val34Leu and the risk of venous thromboembolism in factor V Leiden carriers.
abstract: A mutation in factor XIII (Val34Leu) was reported to protect against venous thromboembolism. We evaluated the effect of Val34Leu on thrombotic risk in 352 factor V Leiden carriers who were first-degree relatives of 132 thrombotic propositi carrying factor V Leiden. The total observation period was 2,594 years in 92 Val34Leu carriers and 7,444 years in 260 non-carriers. The annual incidence of a first episode of venous thromboembolism was 0.31% in Val34Leu carriers and 0.44% in non-carriers [relative risk (RR) for venous thromboembolism: 0.7, 95% CI 0.3-1.5]. Age-specific RR for venous thromboembolism were (for Val34Leu carriers and non-carriers respectively): 1.0 (95% CI 0.3-3.2) in the age group of 15-30 years, 0.4 (95%, CI 0.05-3.0) in the age group of 30-45 years, 0.6 (95% CI 0.1-2.9) in the group aged 45-60 years and 0.5 (95% CI 0.06-4.5) in relatives older than 60 years. In conclusion, the impact of FXIII Val34Leu on the venous thromboembolic risk is modest, suggesting that screening for this mutation in factor V Leiden carriers is not justified.
authors.affiliation: Laboratory for Experimental Internal Medicine, Academic Medical Centre, Amsterdam, The Netherlands.
authors.forename: R F
authors.initials: RF
authors.lastname: Franco
authors.forename: S
authors.initials: S
authors.lastname: Middeldorp
authors.forename: J R
authors.initials: JR
authors.lastname: Meinardi
authors.forename: E C
authors.initials: EC
authors.lastname: van Pampus
authors.forename: P H
authors.initials: PH
authors.lastname: Reitsma
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D016001:Confidence Intervals; D005165:Factor V; D005176:Factor XIII / Q000235:genetics*; D005260:Female; D006720:Homozygote; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009154:Mutation; D018570:Risk Assessment / Q000379:methods; D013923:Thromboembolism / Q000097:blood* / Q000235:genetics; D020246:Venous Thrombosis / Q000097:blood* / Q000235:genetics
chemical_list: C095381:factor V Leiden; D005165:Factor V; D005176:Factor XIII