[A common mutation C677T in the 5,10-methyltetrahydrofolate reductase gene is associated to idiopathic deep venous thrombosis].

Purpose: Moderate hyperhomocysteinemia is a risk factor for deep venous thrombosis. The homozygous C677T methylenetetrahydrofolate reductase (MTHFR) mutation is associated with increased level of total plasma homocysteine. The association between homozygous C677T mutation and deep venous thrombosis is still controversial.

Method: In order to evaluate this association, we studied the prevalence of C677T mutation in 168 patients with confirmed deep venous thrombosis; 31 with an idiopathic deep venous thrombosis (group A) and 137 with thromboembolic event explained by one or more clinical and/or biological risk factors (group B).

Results: The distribution of genotypes was different between group A and B [++/+ -/- -(n(%))] : 9(29)/10(32)/12(39) vs 16(12)/57(42)/64(46) (chi(2) : 6.03; P: 0.049). The comparison between homozygotes and the two other genotypes showed significant statistical relationship between homozygous genotype and idiopathic character of deep venous thrombosis (chi(2) : 6.01; P : 0.014; OR : 3.09 [IC 95% : 1.06-8.53]).

Conclusion: These results suggest that homozygous C677T methylenetetrahydrofolate reductase mutation could be considered as a genetic risk factor for venous thrombosis.