title: Cystathionine beta-synthase polymorphisms and hyperhomocysteinaemia: an association study.
abstract: Hyperhomocysteinaemia is generally accepted as an independent and graded risk factor for both arterial occlusive disease and venous thrombosis. The only way of homocysteine degradation is conversion to cysteine in the transsulfuration pathway in which the regulating step is catalysed by cystathionine beta-synthase (CBS). Mild impairment of CBS function could therefore affect homocysteine concentration, in particular after methionine loading, and consequently cardiovascular disease (CVD) risk. We analysed two silent polymorphisms and one short tandem repeat in the CBS gene (ie 699C-->T, 1080C-->T and -5697 (GT) STR) as genetic markers potentially in linkage disequilibrium with a functional polymorphism. We assessed their association with fasting and post-methionine load homocysteine in 190 patients with arterial occlusive disease, and in 381 controls. No differences in CBS genotype frequencies between cases and controls were found, nor was a particular CBS genotype associated with an elevated risk of arterial occlusive disease. Although we did find a high rate of linkage disequilibrium between the two single nucleotide polymorphisms and the GT STR, none of the genotypes defined by the three CBS variants studied showed an association with elevated fasting, post-load or increase upon methionine loading homocysteine concentrations. In conclusion, we did not find any indication that genetic variation in the CBS gene is associated with increased homocysteine concentrations.
authors.affiliation: Laboratory of Pediatrics and Neurology, University Medical Center Nijmegen, The Netherlands.
authors.forename: Karin J A
authors.initials: KJ
authors.lastname: Lievers
authors.forename: Leo A J
authors.initials: LA
authors.lastname: Kluijtmans
authors.forename: Sandra G
authors.initials: SG
authors.lastname: Heil
authors.forename: Godfried H J
authors.initials: GH
authors.lastname: Boers
authors.forename: Petra
authors.initials: P
authors.lastname: Verhoef
authors.forename: Martin
authors.initials: M
authors.lastname: Den Heijer
authors.forename: Frans J M
authors.initials: FJ
authors.lastname: Trijbels
authors.forename: Henk J
authors.initials: HJ
authors.lastname: Blom
mesh_terms: D000328:Adult; D003541:Cystathionine beta-Synthase / Q000235:genetics*; D005215:Fasting; D005260:Female; D020022:Genetic Predisposition to Disease; D006710:Homocysteine / Q000097:blood; D006801:Humans; D020138:Hyperhomocysteinemia / Q000235:genetics*; D015810:Linkage Disequilibrium; D008297:Male; D008875:Middle Aged; D011110:Polymorphism, Genetic; D020641:Polymorphism, Single Nucleotide; D014652:Vascular Diseases / Q000235:genetics
chemical_list: D006710:Homocysteine; D003541:Cystathionine beta-Synthase