| BackgroundsDeep venous thrombosis (DVT) in medicine is a serious and common disease affecting all age groups. Its causes include a variety of pathological conditions and it often lead to hospitalization of patients, and severe conditions that require urgent intervention. About one and a half century ago, Rudolph Virchow proposed the main determinants that lead to DVT, summarizing that blood stasis, changes in the vessel wall, and blood hypercoagulability are the main mechanisms of the body for developing venous thrombosis. This theory is still applicable today and almost all of factors that lead to thrombosis, either systemie or of molecular level, have essentially affected one of the three mechanisms.There are a lot of mechanisms lead to the susceptibility to venous thrombosis clinically.which can be divided into two main categories:one category includes direct or indirect causes by trauma, systemic disease, or physiological state changes such as pregnancy, high-altitude, surgery, malignancy, body immobilization, and so on. The other is due to genetic mutations involving in the abnormal blood clotting mechanism. At present, due to the rapid progress of molecular genetics researches, and more accurate in vitro experiments, it has been found that in more than30%of individuals, genetic mutations participate in the mechanism of occurrence of DVT. Domestic research in this area is relatively rare. The present study is divided into two parts, respectively, related to endothelial protein C receptor A6936G gene polymorphism and methylenetetrahydrofolate reductase C677T gene polymorphism. Moreover, the relationship between the two polymorphisms and DVT were also studied.Part1Deep Venous Thrombosis has Relationship with Methylenetetrahydropholate Reductase C677T Gene Polymorphism and HyperhomocysteinemiaMethylenetetrahydrofolate reductase (MTHFR) plays a key role in homocysteine (Hey) metabolism,which can catalyze the reaction from5,10-methylenetetrahydrofolate to5-methylenetetrahydrofolate, thus becoming the methyl donor involved in the conversion from vitamin B12-dependent homocysteine to methionine. Reducing MTHFR concentration,it tend to be observed that thermal instability form of the enzyme, it will lead to high homocysteine concentration, which is characterized by mild to moderate increasing in plasma total homocysteine concentration. In vascular occlusive disease, the relationship with hyperhomocysteinemia has been reported. Recent studies have also demonstrated that high plasma total homocysteine concentration is a risk factor for deep venous thrombosis (DVT) in the general population.MTHFR gene polymorphisms have been reported to be associated with high plasma homocysteine concentration. MTHFR gene C677T,can develop thermal instability and reduce the enzyme activity in vitro to a certain extent. C677T mutation in the homozygous individuals can moderately increase plasma homocysteine concentration, especially under the condition of low plasma folate level. Homozygotes of the C677T polymorphism in some studies have been regarded as a risk factor for venous thrombosis, however, not all studies support this conclusion. Opposite conclusions exist in some researches.Moreover, few domestic research has reported in this area.Objective and Methods To explore the relationship of blood I Icy levels and MTHFR C677T gene polymorphism and DVT incidence, in this case-control study, we analyzed the frequency of genotypes with MTHFR C677T polymorphism in DVT patients compared with normal individuals without DVT. In addition, we evaluated the association between this polymorphism and plasma Hey levels. PCR-RFLP was used to investigate the relationship between MTHFR C677T genotypes and DVT. The Hey levels were measured by enzyme-linked immunosorbent assay (ELISA) in DVT patients and control subjects.ResultsThere are3genotypes,CC, CT and TT genotypes,in the MTHFR gene at position677in the two groups. The frequencies of T allele in DVT group was significantly higher than in the controls. The MTHFR C677T frequencies TT genotype was also significantly higher than in the controls. Compared with the CC genotype, the TT genotype was significantly correlated with a increased risk of DVT (OR=3.200;95%CI,1.293-7.922, P=0.010). Compared with the C allel, the T allel was significantly correlated with a increased risk of DVT(OR=1.712;95%CI,1.095-2.675, P=0.018).The plasma level of I Icy in the DVT group was significantly higher than that in the control group. And the level of Hcy in subjects with TT genotype was significantly higher than in subjects with CT genotype, meanwhile, the level of Hcy in subjects with CT genotype was significantly higher than in subjects with CC genotype.ConclusionThe analysis in this study showed that the MTHFR677TT homozygote was a significant risk factor for DVT. And the I allel was correlated with a increased risk of DVT. There are differences in I Icy levels among the different genotypes impling that the mutation accounts for the changes of Hey levels. Hcy levels are elevated in DVT. In conclusion, our present observations allow us to suggest that the C677T mutation of the MTHFR gene, which is possible to cause hyperhomocysteinemia, is probably one of the candidate genetic risk factors of DVT. Part2Endothelial cell protein C receptor gene6936A/G polymorphism is associated with deep venous thrombosisProtein C (PC) system is an important natural anticoagulant mechanism. Under the condition of the existance of its coenzyme protein S, activated protein C (aPC) can make inactivation of factor Va and â…§a, thereby reducing thrombin generation. The activation of endothelial cell protein C receptor (EPCR), is a vascular endothelial cell surface receptor of newly discovered. This receptor combining with almost the same affinity with PC or aPC,can accelerate the activation of PC.Whereas, soluble endothelial cell protein C receptor (sEPCR) gets the effect of metalloproteinase, shedding from EPCR, being also combined with PC and aPC similar affinity. sEPCR is able to block the aPC with the combination of phospholipids and eliminate its effects of inactivation for factor Va, thereby inhibiting the anticoagulant activity of aPC. Several factors can influence level of sEPCR including gene polymorphisms. For further investigating the relation between EPCR A6936G polymorphism and DVT,we performed this case-control study. The relation between EPCR A6936G polymorphism and sEPCR level was also studied.Objective and MethodsIn this study, the aim of this study was to explore the role of gene mutation in the DVT formation. PCR-RFLP was used to investigate the relationship between EPCR A6936G polymorphism and DVT. The plasma soluble endothelial cell protein C receptor (sEPCR) levels were measured by enzyme-linked immunosorbent assay (ELISA) method in DVT patients and control subjects. All statistical analysis was performed for confirmation the possible relationships.ResultsThree genotypes, AA, AG and GG, in the EPCR gene at position6936were noted in the DVT group as well as in the control group. In the DVT group, the frequency of mutational genotypes was significantly higher than that in the control group (P<0.05). Furthermore, the frequency of the G allele in the DVT group was significantly higher than that in the control group (OR=2.178;95%CI,1.159-4.093). The plasma level of sEPCR in the DVT group was significantly higher than that in the control group. And the level of sEPCR in subjects with GG genotype was significantly higher than in subjects with AG genotype, meanwhile, the level of Hey in subjects with AG genotype was significantly higher than in subjects with AA genotype.ConclusionIn this study, the results suggest an increased risk for venous thrombosis in EPCR6936mutational genotypes. The G allele indicates susceptibility to DVT and is associated with DVT pathogenesis. Moreover, our results indicate that the plasma sEPCR level is associated with the A6936G polymorphism of the EPCR gene. The plasma sEPCR level was elevated in DVT patients. Our findings suggest that the EPCR gene A6936G polymorphism may be a candidate risk factor for DVT. |
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