title: Genetic variation in heme oxygenase 1 (HMOX1) and the risk of recurrent venous thromboembolism.
abstract: OBJECTIVE
  Products of heme oxygenase 1 (HO1) possess antithrombotic properties, and impairment of HO1 activity may contribute to thrombus formation. Transcriptional activity of long GT-repeat alleles in HO1 gene (HMOX1) is lower as compared with short alleles. We hypothesize that these long alleles are associated with decreased HO1 anticoagulant activity and, thus, an increased risk of thrombosis..
  
  
  METHODS
  In a prospective cohort study, we followed 860 patients with a first VTE, and investigated the impact of a promoter GT-dinucleotid length polymorphism in HOMX1 on the risk of recurrent venous thromboembolism (VTE).
  
  
  RESULTS
  Allele groups short (S), medium (M) and long (L) of the promoter GT-dinucleotide length polymorphism were distinguished. L-alleles, but not M- or S-alleles, were found to be more frequent among patients with recurrence. Heterozygous carriers of L-alleles had a two-fold higher relative risk of recurrence [(RR 2.2 (95% CI: 1.4-3.4)] as compared to wild type, which was independent of other thrombotic risk factors. At five years, the cumulative probability of recurrence was 18% (95% CI: 15%-22%) in patients without an L-allele compared to 32% (95% CI: 19%-46%) in patients heterozygous for the L-allele (P = .001).
  
  
  CONCLUSIONS
  Patients with first VTE and long GT-repeat alleles in HMOX1 have an increased risk of recurrence. Genetically determined alterations in HO1 function may represent a new pathomechanism in VTE.
authors.affiliation: Institute of Medical and Chemical Laboratory Diagnostics, Medical University of Vienna, Vienna, Austria.
authors.forename: Stefan
authors.initials: S
authors.lastname: Mustafa
authors.forename: Ansgar
authors.initials: A
authors.lastname: Weltermann
authors.forename: Robert
authors.initials: R
authors.lastname: Fritsche
authors.forename: Claudia
authors.initials: C
authors.lastname: Marsik
authors.forename: Oswald
authors.initials: O
authors.lastname: Wagner
authors.forename: Paul A
authors.initials: PA
authors.lastname: Kyrle
authors.forename: Sabine
authors.initials: S
authors.lastname: Eichinger
mesh_terms: D000328:Adult; D001317:Austria; D001777:Blood Coagulation / Q000235:genetics*; D018900:Dinucleotide Repeats; D005260:Female; D005500:Follow-Up Studies; D005787:Gene Frequency; D020022:Genetic Predisposition to Disease; D051547:Heme Oxygenase-1 / Q000235:genetics*; D006579:Heterozygote; D006801:Humans; D008297:Male; D008875:Middle Aged; D011110:Polymorphism, Genetic; D011401:Promoter Regions, Genetic; D011446:Prospective Studies; D012008:Recurrence; D018570:Risk Assessment; D012307:Risk Factors; D013997:Time Factors; D054556:Venous Thromboembolism / Q000097:blood / Q000201:enzymology / Q000235:genetics*
chemical_list: C496541:HMOX1 protein, human; D051547:Heme Oxygenase-1