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Background: Moderate hyperhomocysteinaemia is a risk factor for venous thromboembolism. We do not know whether this risk depends on homocysteine itself or on components of the homocysteine remethylation pathway, such as methylfolate. We did a case-control study to analyse the relation between the major components of the homocysteine remethylation pathway and risk of venous thromboembolism., Methods: We measured concentrations of homocysteine, methionine, and folate in plasma, total folate and methylfolate in red-blood cells, and 5,10-methylenetetrahydrofolate reductase (MTHFR) C677T genotype and other known risk factors for venous thromboembolic disease in 243 patients with deep vein thrombosis or pulmonary embolism and controls matched for sex and age., Findings: Concentrations in plasma of homocysteine differed significantly between cases and controls. We noted a strong concentration-dependent association between concentrations of methylfolate in red-blood cells and risk of venous thromboembolism. The adjusted conditional odds ratio ranged from 1.0 for methylfolate 249 microg/L or greater to 7.1 (3.2-15.8) for methylfolate 141 microg/L or less. Methionine concentrations below the median were also independently associated with raised risk of venous thromboembolic disease, as were established risk factors such as high body-mass index, history of cancer, family history of thromboembolism, oral contraceptive use, and factor V Leiden mutation. Furthermore, the association between concentrations of methylfolate in red-blood cells and risk of thromboembolism varied according to MTHFR C677T genotype., Interpretation: Measurement of methylfolate concentrations in red-blood cells might help to identify people at risk of venous thromboembolism.

Purpose: Arterial or venous thromboses are frequent in patients with homocystinuria. Because severe homocystinuria is rare, prevalence of thrombosis, especially in France, is still unknown., Methods: Review of the clinical outcome of 37 patients with homocystinuria due to cystathionine-cystathionine beta-synthase deficiency (34) and 5,10-methylenetetrahydrofolate reductase (three) lead us to describe vascular complications occurring in 12 (32%) of them., Results: Venous thromboembolism is the earlier and the most frequent one and is mainly found in untreated late-diagnosed cases. Under specific treatment of homocystinuria, thromboses are rare and always a complication of surgery associated with high thromboembolic risk. Association with factor V Leiden increased the risk of venous thrombosis.

Ferritin, iron storage protein, presents two types of subunits, H and L, the respective proportions of which varying with the tissue of origin and defining molecules called isoferritins. This work attempts to compare four human ferritins (from liver, spleen, heart and placenta) by means of the microcomplement fixation technique. Results show that placenta and liver ferritins are closely related, while slight but significant differences appear between liver, spleen and heart ferritins. These differences are obviously less important compared to those observed between ferritins from different species of origin, as shown by the results expressed in terms of index of dissimilarity or immunological distance. Those results are fully consistent with the elementary aminoacid composition as well as with the relative proportions of H and L subunits among the various types of human isoferritins we have studied.