title: A second common variant in the methylenetetrahydrofolate reductase (MTHFR) gene and its relationship to MTHFR enzyme activity, homocysteine, and cardiovascular disease risk.
abstract: Molecular defects in genes encoding enzymes involved in homocysteine metabolism may account for mild hyperhomocysteinemia, an independent and graded risk factor for cardiovascular disease (CVD). We examined the relationship of two polymorphisms in the methylenetetrahydrofolate reductase (MTHFR) gene, the 677C-->T and 1298A-->C variants, to MTHFR activity, homocysteine concentrations, and risk of CVD in a population of 190 vascular disease patients and 601 apparently healthy controls. The mean specific and residual MTHFR activities were significantly lower in 677CT and 677TT individuals (both P<0.001). The 1298A-->C mutation alone showed no effect on MTHFR activities. However, when the 677C-->T genotype was taken into account, the 1298A-->C mutation also caused a significant decrease in MTHFR activities, which was observed in both the homozygous 1298CC (P<0.001) and the heterozygous 1298AC states (P=0.005). Both the 677TT as the 677CT genotypes were associated with significantly higher fasting and postload homocysteine levels than 677CC (P<0.001 and P=0.003, respectively). The 1298A-->C mutation had no effect on fasting or postload homocysteine levels. Since homocysteine itself is considered to be positively associated with the risk of CVD, these findings indicate that the 1298A-->C mutation cannot be considered a major risk factor for CVD.
authors.affiliation: Department of Pediatrics, University Medical Center, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands.
authors.forename: K J
authors.initials: KJ
authors.lastname: Lievers
authors.forename: G H
authors.initials: GH
authors.lastname: Boers
authors.forename: P
authors.initials: P
authors.lastname: Verhoef
authors.forename: M
authors.initials: M
authors.lastname: den Heijer
authors.forename: L A
authors.initials: LA
authors.lastname: Kluijtmans
authors.forename: N M
authors.initials: NM
authors.lastname: van der Put
authors.forename: F J
authors.initials: FJ
authors.lastname: Trijbels
authors.forename: H J
authors.initials: HJ
authors.lastname: Blom
mesh_terms: D000328:Adult; D002318:Cardiovascular Diseases / Q000235:genetics*; D005215:Fasting; D005260:Female; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006710:Homocysteine / Q000378:metabolism*; D006801:Humans; D008297:Male; D042965:Methylenetetrahydrofolate Reductase (NADPH2); D008875:Middle Aged; D009154:Mutation; D000587:Oxidoreductases Acting on CH-NH Group Donors / Q000235:genetics* / Q000378:metabolism*; D011110:Polymorphism, Genetic; D012307:Risk Factors
chemical_list: D006710:Homocysteine; D000587:Oxidoreductases Acting on CH-NH Group Donors; D042965:Methylenetetrahydrofolate Reductase (NADPH2)