Hyperhomocysteinemia, resulting from a deficiency in the conversion of homocysteine to cystathionine, constitutes an independent risk factor for vascular diseases. The 844ins68 mutation of the cystathionine-beta-synthetase gene is an additional risk factor for deep venous thrombosis. The aim of this study was to evaluate the frequency of the 844ins68 mutation of the cystathionine-beta-synthetase gene in deep venous thrombosis. In a case control study, 95 patients with deep venous thrombosis were evaluated in respect to the presence of the 844ins68 mutation on exon 8 of the cystathionine-beta-synthetase gene. The inclusion criterion included the presence of deep venous thrombosis confirmed by duplex or phlebography. A control group was formed consisting of 95 blood donors, without previous history of venous thrombosis with data such as gender, age and race similar to the study group. Five milliliters of venous blood were collected in EDTA anticoagulant from all the members of both groups. The DNA was extracted from the leukocytes by te DTAB and CTAB methods. Detection of the gene mutation was made by amplification by PCR, using primers for the insertion region and observed by 2% agarose gel electrophoresis using ethidium bromide stain. The fragment corresponding to the normal allele contains 184 base pairs and the mutant allele 252 base pairs. The Fisher exact test was utilized in the analysis of the results. Heterozygote individuals for the mutation were evidenced in 14.73% of the patients and in 3.1% of the control group (p-value = 0.009). The frequency of the mutant allele demonstrated a significant difference (0.074 for the patients versus 0.016 for the control group) (p-value = 0.01). No homozygotic individuals were found.
Cystathionine-beta-synthetase; deep venous thrombosis; prevalence; polymorphism
