title: The effect of a promoter polymorphism in the heme oxygenase-1 gene on the risk of ischaemic cerebrovascular events: the influence of other vascular risk factors.
abstract: Heme oxygenase-1 (HO-1) has been demonstrated to exert potent anti-oxidant and anti-inflammatory effects in the context of atherosclerotic vascular disease, and therefore was referred to as a potential vascular protective factor. A (GT)n dinucleotide repeat polymorphism in the HO-1 promoter has been shown to modulate HO-1 gene expression. Short (<25) GT repeats were associated with HO-1 up-regulation, and therefore may influence susceptibility to ischaemic vascular events. We investigated the association of HO-1 repeat length with the risk of cerebrovascular events in a case control study and assessed possible interrelations with vascular risk factors. We determined the number of GT repeats in the HO-1 promoter in 399 patients with ischaemic cerebrovascular events and 398 healthy controls and compared the frequencies of short (<25) repeat (class S) and long (> or =25) repeat (class L) alleles after adjustment for potentially confounding factors. Genotype distributions of S/S, S/L and L/L in patients were 9.8% (n=39), 45.1% (n=180) and 45.1% (n=180), which was similar to the distribution in controls with 11.5% (n=46), 44.5% (n=177) and 44.0% (n=175). In the presence of vascular risk factors, the HO-1 genotype became functionally relevant: in patients without hyperlipidemia the S/S genotype exerted a protective effect on the development of ischaemic cerebrovascular events (OR 0.2; 95% CI 0.1-0.6), while this effect was no longer present in hyperlipidemic patients. Short (<25 GT) repeats in the HO-1 gene promoter confer a reduced risk for cerebrovascular events in individuals with normal plasma lipid levels. This may explain controversial findings in different populations.
authors.affiliation: Clinical Institute for Medical and Chemical Laboratory Diagnostics, Medical University Vienna, Vienna, Austria.
authors.forename: Marion
authors.initials: M
authors.lastname: Funk
authors.forename: Georg
authors.initials: G
authors.lastname: Endler
authors.forename: Martin
authors.initials: M
authors.lastname: Schillinger
authors.forename: Stefan
authors.initials: S
authors.lastname: Mustafa
authors.forename: Kety
authors.initials: K
authors.lastname: Hsieh
authors.forename: Markus
authors.initials: M
authors.lastname: Exner
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Lalouschek
authors.forename: Christine
authors.initials: C
authors.lastname: Mannhalter
authors.forename: Oswald
authors.initials: O
authors.lastname: Wagner
mesh_terms: D000328:Adult; D000368:Aged; D000483:Alleles; D016022:Case-Control Studies; D005260:Female; D005787:Gene Frequency; D014644:Genetic Variation; D006419:Heme Oxygenase (Decyclizing) / Q000235:genetics*; D051547:Heme Oxygenase-1; D006801:Humans; D008297:Male; D008565:Membrane Proteins; D018895:Microsatellite Repeats; D008875:Middle Aged; D018598:Minisatellite Repeats; D011110:Polymorphism, Genetic; D011401:Promoter Regions, Genetic; D012189:Retrospective Studies; D012307:Risk Factors; D020521:Stroke / Q000235:genetics*
chemical_list: D008565:Membrane Proteins; C496541:HMOX1 protein, human; D006419:Heme Oxygenase (Decyclizing); D051547:Heme Oxygenase-1