[Effect of hyperhomocysteinemia and methylenetetrahydrofolate reductase 677C --> T mutation in venous thromboembolism risk of young adults].

BACKGROUND AND OBJECTIVE To investigate whether hyperhomocysteinemia and methylenetetrahydrofolate reductase (MTHFR) 677C --> T mutation are associated with venous thromboembolism in young Spanish adults. PATIENTS AND METHOD One hundred adult patients younger than 50 years and 177 controls with similar age and gender. RESULTS Hyperhomocysteinemia was present in 21% of the patients and 3.3% of the controls (p < 0.001), and MTHFR 677C --> T mutation was found in 25 and 14.7%, respectively (p = 0.03). Odds ratio (OR) for thromboembolism in hyperhomocysteinemic patients was 7.5 (95% CI, 2.9-19.2; p < 0.001), and in patients with MTHFR 677C --> T mutation the OR was 1.9 (95% CI, 1.1-3.5; p = 0.03). In a subgroup of 76 patients without other thrombogenic factors, thromboembolism persisted associated with hyperhomocysteinemia, yet an association with MTHFR 677C --> T mutation was not confirmed. CONCLUSIONS Hyperhomocysteinemia, but not MTHFR 677C --> T mutation, is a risk factor for venous thromboembolism in young adults without other thrombogenic factors.