Markers of Hereditary Thrombophilia with Unclear Significance

Thrombophilia leads to an increased risk of venous thromboembolism. Widely accepted risk factors for thrombophilia comprise deficiencies of protein C, protein S, and antithrombin, as well as the factor V "Leiden" mutation, the prothrombin G20210A mutation, dysfibrinogenemia, and, albeit less conclusive, increased levels of factor VIII. Besides these established markers of thrombophilia, risk factors of unclear significance have been described in the literature. These inherited risk factors include deficiencies or loss-of-activity of the activity of ADAMTS13, heparin cofactor II, plasminogen, tissue factor pathway inhibitor (TFPI), thrombomodulin, protein Z (PZ), as well as PZ-dependent protease inhibitor. On the other hand, thrombophilia has been linked to the gain-of-activity, or elevated levels, of α2-antiplasmin, angiotensin-converting enzyme, coagulation factors IX (FIX) and XI (FXI), fibrinogen, homocysteine, lipoprotein(a), plasminogen activator inhibitor-1 (PAI-1), and thrombin-activatable fibrinolysis inhibitor (TAFI). With respect to the molecular interactions that may influence the thrombotic risk, more complex mechanisms have been described for endothelial protein C receptor (EPCR) and factor XIII (FXIII) Val34Leu. With focus on the risk for venous thrombosis, the present review aims to give an overview on the current knowledge on the significance of the aforementioned markers for thrombophilia screening. According to the current knowledge, there appears to be weak evidence for a potential impact of EPCR, FIX, FXI, FXIII Val34Leu, fibrinogen, homocysteine, PAI-1, PZ, TAFI, and TFPI on the thrombotic risk.

Thrombophilic risk factors are laterally associated with Apolipoprotein E gene polymorphisms in deep vein thrombosis patients: An Indian study

INTRODUCTION

Deep vein thrombosis is a multifactorial disease with many acquired and genetic risk factors. Polymorphism in the APOE gene is an upcoming potential pathogenic factor whose role is unclear in deep vein thrombosis.

METHODS

An equal number of deep vein thrombosis cases and controls (N = 100, each) were investigated for APOE gene polymorphisms along with known acquired and hereditable thrombophilic risk factors. APOE genotyping was done by polymerase chain reaction.

RESULTS

The ε3/ε4 and ε2/ε3 APOE genotypes were commoner in deep vein thrombosis cases than controls but not statistically significant ( ε3/ε4 → 18% versus 11%, OR = 1.776, CI = 0.792-3.984, p = 0.16; ε2/ε3 →10% versus 9%, OR = 1.123, CI = 0.436-2.895, p = 0.809). However, the following risk factors were found to be laterally associated with APOE genotypes in cases of deep vein thrombosis: pregnancy with ε2/ε3 genotype positivity (N = 29; p = 0.019), recurrent pregnancy loss with ε3/ε3 genotype (N = 29; p = 0.016), normal antithrombin levels with ε3/ε3 genotype (N = 62; p = 0.03) and non-O blood group with ε3/ε4 genotype (N = 100; p = 0.023).

CONCLUSION

APOE genotypes have shown only a modest association with deep vein thrombosis and were not statistically significant. A lateral association of these genotypes with thrombophilic risk factors was observed which may be investigated further for the possible pathogenetic mechanisms and their therapeutic implications.

Elevated Levels of LDL-C are Associated With ApoE4 but Not With the rs688 Polymorphism in the LDLR Gene

INTRODUCTION

Apolipoprotein E (ApoE) 4 isoform has been associated with elevated levels of cholesterol, low-density lipoprotein cholesterol (LDL-C), and triglycerides (TGs), meanwhile several polymorphisms in the LDL receptor (LDLR) gene have been associated with increased levels of total cholesterol and LDL-C.

MATERIAL AND METHODS

We studied 400 women from Southwest Mexico. Anthropometric features and biochemical profile were evaluated, and genotyping of single nucleotide polymorphisms rs429358 and rs7412 in the APOE gene and rs688 in the LDLR gene was determined by TaqMan assays.

RESULTS

We found significant association between LDL-C (odds ratio [OR] = 3.3, 95% confidence interval [CI]: 1.9-5.7) and marginal association with TG (OR = 1.7, 95% CI: 1.0-2.9) of atherogenic risk in women carriers of the ApoE4 isoform compared to ApoE3. The TT genotype of rs688 in the LDLR gene was not found to be associated with elevated levels of total cholesterol or LDL-C.

CONCLUSION

Our results show that carrier women of the ApoE4 isoform are more likely to have elevated levels of LDL-C and therefore increased risk of developing atherosclerosis.

Apolipoprotein E polymorphism is associated with lower extremity deep venous thrombosis: color-flow Doppler ultrasound evaluation

Introduction

Apolipoprotein E (apoE) is a member of apolipoprotein family, and its gene polymorphisms seem to have some impact among patients with cardiovascular disease. However, its role in the lower extremity deep venous thrombosis (LEDVT) has not been well studied. The objective of this study was to investigate the potential association between APOE gene polymorphisms and LEDVT.

Materials and methods

A hospital-based case–control study was conducted in 300 patients with LEDVT by color-flow Doppler ultrasound and 300 age- and gender-matched healthy controls. Polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) assay was applied to assess the APOE gene polymorphisms.

Results

Patients with LEDVT had a significantly higher frequency of APOE E3/E4 genotype [odds ratio (OR) =1.48, 95% confidence interval (CI) = 1.05, 2.10; P = 0.03] than healthy controls. When stratifying by family history of LEDVT, it was found that patients with positive family history of LEDVT had a significantly higher frequency of APOE E3/E4 genotype (OR =1.68, 95% CI = 1.04, 0.95; P = 2.70). When stratifying by smoking status, presence of varicose veins, type 2 diabetes mellitus and any hormone administration before, no significant differences were found in any groups.

Conclusion

Our study suggested that APOE E3/E4 genotype was associated with a higher LEDVT risk. Additional studies are needed to confirm this finding.