Carmen H. Tong

Gene variants associated with deep vein thrombosis.

CONTEXT The genetic causes of deep vein thrombosis (DVT) are not fully understood. OBJECTIVE To identify single-nucleotide polymorphisms (SNPs) associated with DVT. DESIGN, SETTING, AND PATIENTS We used 3 case-control studies of first DVT. A total of 19 682 gene-centric SNPs were genotyped in 443 cases and 453 controls from the Leiden Thrombophilia Study (LETS, 1988-1992). Twelve hundred six SNPs associated with DVT were reinvestigated in the Multiple Environmental and Genetic Assessment of Risk Factors for Venous Thrombosis study (MEGA-1, 1999-2004) in a subset of 1398 cases and 1757 controls. Nine SNPs associated with DVT in both LETS and MEGA-1 were investigated a third time in 1314 cases and 2877 controls from MEGA-2, a second subset of MEGA. Additional SNPs close to one SNP in CYP4V2 were genotyped in LETS and MEGA-1. MAIN OUTCOME MEASURE Odds ratios (ORs) for DVT were estimated by logistic regression. False discovery rates served to investigate the effect of multiple hypothesis testing. RESULTS Of 9 SNPs genotyped in MEGA-2, 3 were strongly associated with DVT (P < .05; false discovery rate < or =.10): rs13146272 in CYP4V2 (risk allele frequency, 0.64), rs2227589 in SERPINC1 (risk allele frequency, 0.10), and rs1613662 in GP6 (risk allele frequency, 0.84). The OR for DVT per risk allele was 1.24 (95% confidence interval [95%CI], 1.11-1.37) for rs13146272, 1.29 (95% CI, 1.10-1.49) for rs2227589, and 1.15 (95% CI, 1.01-1.30) for rs1613662. In the region of CYP4V2, we identified 4 additional SNPs (in CYP4V2, KLKB1, and F11) that were also associated with both DVT (highest OR per risk allele, 1.39; 95% CI, 1.11-1.74) and coagulation factor XI level (highest increase per risk allele, 8%; 95% CI, 5%-11%). CONCLUSIONS We identified SNPs in several genes that were associated with DVT. We also found SNPs in the region around the SNP in CYP4V2 (rs13146272) that were associated with both DVT and factor XI levels. These results show that common genetic variation plays an important role in determining thrombotic risk.

Association of the Trp719Arg Polymorphism in Kinesin-Like Protein 6 With Myocardial Infarction and Coronary Heart Disease in 2 Prospective Trials The CARE and WOSCOPS Trials

OBJECTIVES We asked whether 35 genetic polymorphisms, previously found to be associated with cardiovascular disease, were associated with myocardial infarction (MI) in the CARE (Cholesterol and Recurrent Events) trial and with coronary heart disease (CHD) in the WOSCOPS (West of Scotland Coronary Prevention Study) trial and whether the risk associated with these polymorphisms could be reduced by pravastatin treatment. BACKGROUND Identification of genetic polymorphisms associated with CHD may improve assessment of CHD risk and understanding of disease pathophysiology. METHODS We tested the association between genotype and recurrent MI in the CARE study and between genotype and primary CHD in the WOSCOPS trial using regression models that adjusted for conventional risk factors: Cox proportional hazards models for the CARE study and conditional logistic regression models for a nested case-control study of the WOSCOPS trial. RESULTS We found that Trp719Arg (rs20455) in KIF6 was associated with coronary events. KIF6 encodes kinesin-like protein 6, a member of the molecular motor superfamily. In placebo-treated patients, carriers of the KIF6 719Arg allele (59.4% of the CARE trial cohort) had a hazard ratio of 1.50 (95% confidence interval [CI] 1.05 to 2.15) in the CARE trial and an odds ratio of 1.55 (95% CI 1.14 to 2.09) in the WOSCOPS trial. Among carriers, the absolute risk reduction by pravastatin was 4.89% (95% CI 1.81% to 7.97%) in the CARE trial and 5.49% (95% CI 3.52% to 7.46%) in the WOSCOPS trial. CONCLUSIONS In both the CARE and the WOSCOPS trials, carriers of the KIF6 719Arg allele had an increased risk of coronary events, and pravastatin treatment substantially reduced that risk.

Polymorphism in KIF6 gene and benefit from statins after acute coronary syndromes: results from the PROVE IT-TIMI 22 study

OBJECTIVES We explored whether the benefit of intensive versus moderate statin therapy would be greater in carriers of KIF6 719Arg than in noncarriers. BACKGROUND The 719Arg variant of Trp719Arg (rs20455), a polymorphism in kinesin-like protein 6, is associated with greater risk of coronary events and greater benefit from pravastatin versus placebo. METHODS We genotyped 1,778 acute coronary syndrome patients within the PROVE IT-TIMI 22 (Pravastatin or Atorvastatin Evaluation and Infection Therapy: Thrombolysis in Myocardial Infarction 22) trial and investigated different intensities of statin therapy in carriers of 719Arg and in noncarriers using Cox proportional hazards models that adjusted for traditional risk factors. RESULTS Benefit from intensive, compared with moderate, statin therapy was significantly greater in the 59% of the cohort who were carriers (hazard ratio [HR] 0.59, 95% confidence interval [CI] 0.45 to 0.77) than in those who were noncarriers (HR 0.94, 95% CI 0.70 to 1.27; p = 0.018 for interaction between 719Arg carrier status and treatment). Absolute risk reduction was 10.0% in carriers versus 0.8% in noncarriers. The benefit of intensive therapy in carriers was significant as early as day 30 of therapy. Carriers and noncarriers did not differ in on-treatment low-density lipoprotein cholesterol, triglyceride, or C-reactive protein (CRP) levels. CONCLUSIONS Carriers of 719Arg receive significantly greater benefit from intensive statin therapy than do noncarriers, a superior benefit that appears to be due to a mechanism distinct from lipid or CRP lowering. Functional studies of the KIF6 kinesin are warranted, given the consistent association of Trp719Arg with risk of coronary events and statin benefit.

A Polymorphism in the Protease-Like Domain of Apolipoprotein(a) Is Associated With Severe Coronary Artery Disease

Objectives—The purpose of this study was to identify genetic variants associated with severe coronary artery disease (CAD). Methods and Results—We used 3 case-control studies of white subjects whose severity of CAD was assessed by angiography. The first 2 studies were used to generate hypotheses that were then tested in the third study. We tested 12 077 putative functional single nucleotide polymorphisms (SNPs) in Study 1 (781 cases, 603 controls) and identified 302 SNPs nominally associated with severe CAD. Testing these 302 SNPs in Study 2 (471 cases, 298 controls), we found 5 (in LPA, CALM1, HAP1, AP3B1, and ABCG2) were nominally associated with severe CAD and had the same risk alleles in both studies. We then tested these 5 SNPs in Study 3 (554 cases, 373 controls). We found 1 SNP that was associated with severe CAD: LPA I4399M (rs3798220). LPA encodes apolipoprotein(a), a component of lipoprotein(a). I4399M is located in the protease-like domain of apolipoprotein(a). Compared with noncarriers, carriers of the 4399M risk allele (2.7% of controls) had an adjusted odds ratio for severe CAD of 3.14 (confidence interval 1.51 to 6.56), and had 5-fold higher median plasma lipoprotein(a) levels (P=0.003). Conclusions—The LPA I4399M SNP is associated with severe CAD and plasma lipoprotein(a) levels.

Multiple SNP testing improves risk prediction of first venous thrombosis

There are no risk models available yet that accurately predict a persons risk for developing venous thrombosis. Our aim was therefore to explore whether inclusion of established thrombosis-associated single nucleotide polymorphisms (SNPs) in a venous thrombosis risk model improves the risk prediction. We calculated genetic risk scores by counting risk-increasing alleles from 31 venous thrombosis-associated SNPs for subjects of a large case-control study, including 2712 patients and 4634 controls (Multiple Environmental and Genetic Assessment). Genetic risk scores based on all 31 SNPs or on the 5 most strongly associated SNPs performed similarly (areas under receiver-operating characteristic curves [AUCs] of 0.70 and 0.69, respectively). For the 5-SNP risk score, the odds ratios for venous thrombosis ranged from 0.37 (95% confidence interval [CI], 0.25-0.53) for persons with 0 risk alleles to 7.48 (95% CI, 4.49-12.46) for persons with more than or equal to 6 risk alleles. The AUC of a risk model based on known nongenetic risk factors was 0.77 (95% CI, 0.76-0.78). Combining the nongenetic and genetic risk models improved the AUC to 0.82 (95% CI, 0.81-0.83), indicating good diagnostic accuracy. To become clinically useful, subgroups of high-risk persons must be identified in whom genetic profiling will also be cost-effective.

KIF6 Trp719Arg polymorphism and the effect of statin therapy in elderly patients: results from the PROSPER study

Background Statin therapy has been found to substantially and significantly reduce coronary events in carriers of the KIF6 719Arg variant (rs20455) but not in noncarriers. We investigated whether, among the elderly, statin therapy also significantly reduced coronary events in carriers but not in noncarriers. Design and methods Among 5752 patients of the PROspective Study of Pravastatin in the Elderly at Risk (PROSPER) study, we assessed the effect of pravastatin, compared with placebo, on coronary events according to 719Arg carrier status using proportional hazards models. Results Since benefit from statin therapy in elderly patients has been primarily shown among those with prior vascular disease, we performed analyses in PROSPER patients with prior disease and found that pravastatin therapy significantly reduced events in 719Arg carriers [hazards ratio (HR): 0.66, 95% confidence interval (CI): 0.52–0.86] but not in noncarriers (HR: 0.94, 95% CI: 0.69–1.28), P= 0.09 for interaction between treatment and carrier status. Among those without prior disease, no significant benefit was observed in either carriers or noncarriers. Among those with prior vascular disease in the placebo arm, Trp719Arg heterozygotes were at significantly greater risk, compared with noncarriers (HR: 1.36, 95% CI: 1.03–1.81, P = 0.03); the HR of 719Arg carriers, compared with noncarriers, was 1.28 (95% CI: 0.98–1.69, P =0.07). Conclusion Elderly carriers of the KIF6 719Arg variant with prior vascular disease received significant benefit from pravastatin therapy; no benefit was observed in noncarriers with prior disease or in those without prior disease (carriers or noncarriers).

Genetic variants associated with deep vein thrombosis: the F11 locus.

Summary.  Background : Recent studies have found associations between deep vein thrombosis (DVT) and single nucleotide polymorphisms (SNPs) in a 4q35.2 locus that contains genes encoding factor XI (F11), a cytochrome P450 family member (CYP4V2), and prekallikrein (KLKB1).

Thrombophilias and adverse pregnancy outcomes: results from the Danish National Birth Cohort

Summary.  Background:  Inherited thrombophilias have inconsistently been linked to adverse pregnancy outcomes. Differences in study design, size and population could explain this heterogeneity.

Association Between ADAMTS1 Matrix Metalloproteinase Gene Variation, Coronary Heart Disease, and Benefit of Statin Therapy

Objective—The purpose of this study was to investigate the association between the Ala227Pro polymorphism in the ADAMTS1 metalloproteinase gene and coronary heart disease and benefit from statin therapy in 2 independent cohorts. Methods and Results—The frequency of the ADAMTS1 227Pro minor allele was 0.24 in 2421 male subjects from CARE, a randomized trial of pravastatin versus placebo. In the placebo arm, homozygotes (6.3% of study population) had a significantly increased risk of fatal coronary disease or nonfatal myocardial infarction (D/MI) compared with noncarriers (OR 2.12, 95% CI 1.07 to 4.19, P=0.03), and in the entire study the benefit of pravastatin in reducing the risk of D/MI was greater in these subjects (OR 0.21, 95% CI 0.06 to 0.69) than in heterozygotes (OR 0.74, 95% CI 0.48 to 1.14) or noncarriers (OR 0.99, 95% CI 0.68 to 1.42; Pinteraction=0.044). Results were tested in 1565 male subjects from WOSCOPS, also a randomized trial of pravastatin versus placebo. Similar to the results in CARE, in the placebo arm subjects homozygous for the minor allele were at increased risk of D/MI (OR 1.72, P=0.052) and in the entire study the benefit of pravastatin in reducing D/MI was greater in these subjects (OR 0.24, 95% CI 0.09 to 0.68) than in heterozygotes (OR 0.73, 95% CI 0.48 to 1.11) or noncarriers (OR 0.65, 95% CI 0.20 to 2.09) (Pinteraction=0.029). Conclusions—In men not on pravastatin, those homozygous for the 227Pro allele of ADAMTS1 have a nearly 2-fold increased risk of coronary heart disease events compared with noncarriers. In this high-risk group, treatment with pravastatin is highly efficacious, reducing the odds of fatal coronary disease or nonfatal MI by approximately 75%, as compared with 25% in noncarriers or heterozygotes.

Asp92Asn polymorphism in the myeloid IgA Fc receptor is associated with myocardial infarction in two disparate populations: CARE and WOSCOPS.

Objective—Statins reduce inflammation and risk of myocardial infarction (MI). Because the myeloid IgA Fc receptor encoded by FCAR mediates inflammation, we hypothesized that the FCAR Asp92Asn polymorphism is associated with risk of MI and that this risk would be modified by pravastatin. Methods and Results—In the placebo arm of the Cholesterol and Recurrent Events (CARE) study, male carriers of the 92Asn allele had an adjusted hazard ratio for incident MI of 1.68 (95% CI 1.10 to 2.57); relative risk reduction by pravastatin was 69% in carriers and 12% in noncarriers (Pinteraction=0.007). In the placebo arm of the all-male West of Scotland Coronary Prevention Study (WOSCOPS), carriers had an adjusted odds ratio for incident coronary heart disease (CHD) of 1.46 (90% CI 1.05 to 2.03); for pravastatin compared with placebo treatment, the adjusted odds ratios were 0.55 (95% CI 0.32 to 0.93) in carriers and 0.65 (95% CI 0.51 to 0.83) in noncarriers (Pinteraction=0.55). Conclusions—Carriers of 92Asn had increased risk of MI in CARE and increased odds of CHD in WOSCOPS. Pravastatin significantly reduced risk in carriers in both CARE and WOSCOPS. A genotype by treatment interaction was observed in CARE but not in WOSCOPS.