title: Hyperhomocysteinemia increases the risk of venous thrombosis independent of the C677T mutation of the methylenetetrahydrofolate reductase gene in selected Brazilian patients.
abstract: Fasting total homocysteine (tHcy) and the methylenetetrahydrofolate reductase (MTHFR) C677T mutation were evaluated in 91 patients with venous thromboembolism and without acquired thrombophilia, and in 91 age-matched and sex-matched controls. Hyperhomocysteinemia was detected in 11 patients (12.1%) and in two controls (2.2%), yielding an odds ratio (OR) for venous thrombosis of 6.1 [95% confidence interval (CI), 1.3-28.4]. After excluding 21 patients and four controls with other known genetic risk factors for venous thrombosis, the OR was not substantially changed (7.0; 95% CI, 1.5-33.1). The prevalence of the MTHFR 677TT genotype was not significantly different in patients (9.9%) and in controls (5.5%), with an OR for venous thrombosis of 1.8 (95% CI, 0.6-5.8). Subjects with the MTHFR 677TT genotype showed higher levels of tHcy compared with the 677CC genotype in patients (P = 0.010) and in controls (P = 0.030). In conclusion, we found that fasting hyperhomocysteinemia is a risk factor for venous thrombosis in patients without known acquired thrombophilia and other genetic risk factors for venous thrombosis. Although tHcy levels are significantly higher in those homozygous for the MTHFR C677T mutation, this genotype does not increase the thrombotic risk in our study population.
authors.affiliation: Department of Clinical Medicine, Federal University of São Paulo (UNIFESP), São Paulo, Brazil. vmorelli@osite.com.br
authors.forename: V M
authors.initials: VM
authors.lastname: Morelli
authors.forename: D M
authors.initials: DM
authors.lastname: Lourenço
authors.forename: V
authors.initials: V
authors.lastname: D'Almeida
authors.forename: R F
authors.initials: RF
authors.lastname: Franco
authors.forename: F
authors.initials: F
authors.lastname: Miranda
authors.forename: M A
authors.initials: MA
authors.lastname: Zago
authors.forename: M A E
authors.initials: MA
authors.lastname: Noguti
authors.forename: E
authors.initials: E
authors.lastname: Cruz
authors.forename: J
authors.initials: J
authors.lastname: Kerbauy
mesh_terms: D020413:3' Untranslated Regions / Q000235:genetics; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019943:Amino Acid Substitution; D001938:Brazil / Q000453:epidemiology; D002648:Child; D005215:Fasting / Q000097:blood; D005260:Female; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006801:Humans; D020138:Hyperhomocysteinemia / Q000453:epidemiology*; D008297:Male; D042965:Methylenetetrahydrofolate Reductase (NADPH2); D008875:Middle Aged; D020125:Mutation, Missense; D016017:Odds Ratio; D000587:Oxidoreductases Acting on CH-NH Group Donors / Q000235:genetics*; D017354:Point Mutation; D011110:Polymorphism, Genetic; D011401:Promoter Regions, Genetic / Q000235:genetics; D011516:Prothrombin / Q000235:genetics; D012307:Risk Factors; D019851:Thrombophilia / Q000097:blood / Q000453:epidemiology* / Q000235:genetics; D020246:Venous Thrombosis / Q000453:epidemiology* / Q000209:etiology
chemical_list: D020413:3' Untranslated Regions; D011516:Prothrombin; D000587:Oxidoreductases Acting on CH-NH Group Donors; D042965:Methylenetetrahydrofolate Reductase (NADPH2)