Factors associated with the failure of clopidogrel dose-adjustment according to platelet reactivity monitoring to optimize P2Y12-ADP receptor blockade

Introduction

Inter-individual variability in clopidogrel responsiveness is dependent on genetic polymorphisms. We aimed to investigate the impact of 3 genetic polymorphisms involved in clopidogrel metabolism on a strategy of dose-adjustment according to platelet reactivity (PR) monitoring.

Materiel and methods

This prospective multicenter study enrolled 498 ACS patients undergoing PCI. PR was measured using the Vasodilator-Stimulated Phosphoprotein index (VASP) and a cut-off value of ≥ 50% defined high on-treatment platelet reactivity (HTPR). Genetic polymorphisms of cytochrome (CYP) 2C19, Paraxonase-1 (PON1) and ABCB1 were determined by allele specific PCR. Dose-adjustment was performed using up-to 3 additional loading doses (LD) of 600 mg clopidogrel in order to obtain a VASP < 50% in patients with HTPR following the first LD.

Results

CYP 2C19 2*polymorphism (p = 0.02), but neither PON1 (p = 0.8) nor ABCB1 genotype (p = 0.9), was significantly associated with HTPR. The dose-adjustment strategy failed in 11% of patients. ABCB1 polymorphism was significantly associated with a failed dose-adjustment (FDA) (p = 0.04). No relation was found between the other genotypes and the efficacy of LD adjustment. In multivariate analysis, BMI and ABCB1 polymorphism were the only factors significantly associated with FDA (p = 0.005 and p = 0.04 respectively).

Conclusion

While CYP 2C19 2* is associated with HTPR after 600 mg of clopidogrel, ABCB1 is responsible for the failure of a strategy of loading dose-adjustment according to PR monitoring. These findings may help to define a therapeutic strategy to optimize anti-platelet therapy in ACS patients undergoing PCI.     

The cytochrome 2C19*2 and *3 alleles attenuate response to clopidogrel similarly in East Asian patients undergoing elective percutaneous coronary intervention

Introduction

Carriage of CYP2C19*2 allele is associated with diminished platelet response to clopidogrel. However, the loss-of-function impact of CYP2C19*3 allele on antiplatelet effect of clopidogrel has not been definitely verified. We conducted this study to compare decreased response to clopidogrel according to carriage of CYP2C19*2 vs. *3 allele.

Materials and methods

The study included 190 consecutive Korean patients undergoing elective percutaneous coronary intervention. Light transmittance aggregometry and the VerifyNow P2Y₁₂ assay were used to assess platelet reactivity (PR) at least 12 hours after 300-mg loading of clopidogrel. The cutoff of high on-treatment PR (HPR) was defined as 5 μmol/L ADP-induced PR > 50%. CYP2C19 genotype was analyzed by the SNaPshot method.

Results

Carriers of at least one CYP2C19 variant allele were 115 patients (60.5%), and allelic frequency of CYP2C19*2 and *3 was 30.3% and 6.8%, respectively. PR and the rate of HPR increased proportionally according to the number of CYP2C19 variant allele. Carriage of CYP2C19 variant allele was an only independent predictor of HPR in multivariate analysis. When we compare the effect of allelic carriage, there were no significant differences in platelet measures and the rate of HPR between carriers of CYP2C19*2 and/or *3 allele(s) whether they were intermediate or poor metabolizers.

Conclusion

Carriage of CYP2C19*3 allele is associated with diminished antiplatelet effect of clopidogrel, which may be as potent as the loss-of-function effect of CYP2C19*2 allele.     

Genetic determinants of high on-treatment platelet reactivity in clopidogrel treated Chinese patients

Introduction

Cytochrome P450 (CYP), ATP-binding cassette transporters (ABCB1), and paraoxonase-1 (PON1) play crucial roles in clopidogel absorption and bioactivation. Genetic polymorphisms in these genes have been associated with the variability of the response to clopidogrel, however their contribution to high on-treatment platelet reactivity (HPR) in clopidogrel treated Chinese patients is less known.

Materials and methods

Five-hundred Chinese-Han patients treated with clopidogrel for acute coronary syndrome (ACS) were consecutively recruited from the Department of Geriatric Cardiology, General Hospital of Chinese People’s Liberation Army, from September 2010 to September 2012. We assessed the relations of CYP2C19*2 (rs4244285), CYP2C19*3 (rs4986893), CYP2C19*17 (rs12248560), PON1Q129R (rs662) and ABCB1C3435T (rs1045642) to the platelet aggregation after 5 days maintenance dose of clopidogrel administration, and the risk for HPR. The cutoff of HPR was defined as 20 μmol/L adenosine diphosphate (ADP)-induced platelet aggregation > 50%.

Results

Both CYP2C19*2 and *3 alleles were significantly associated with higher platelet aggregation after 5 days maintenance dose of clopidogrel administration (P < 0.00001and P = 0.042, respectively). The platelet aggregation in carriers of at least one CYP2C19 loss-of-function allele (*2 or *3, accounted for 58% of the study population) was obviously higher than that in non-carriers (P < 0.00001). Patients with the CYP2C19*2 allele had a higher risk of HPR than those with the CYP2C19 wild-type genotype [adjusted hazard ratio (HR), 1.56; 95% confidence interval(CI), 1.04–2.33, P = 0.03]. The carriers of at least one CYP2C19 loss-of-function allele could also predict significantly greater risk of HPR compared with non-carriers (adjusted HR1.79,95% CI: 1.33–2.4,P = 0.003). However, the carriage of CYP2C19*3 alone could not predict the risk of HPR significantly (adjusted HR, 1.5; 95% CI: 0.83–3, P = 0.16). Significant relation of CYP2C19*17, PON1Q129R and ABCB1C3435T to the platelet aggregation was not found.

Conclusion

In clopidogrel treated Chinese patients with ACS, carriers of at least one CYP2C19 loss-of-function allele could predict greater risk of HPR, with the impact mainly attributing to CYP2C19*2. Neither ABCB1 nor PON1 genotype could influence the antiplatelet response of clopidogrel in the cohort of Chinese patients.     

VASP phosphorylation and genetic polymorphism for clopidogrel resistance in Chinese patients with non-cardioembolic ischemic stroke

Background

Clopidogrel resistance(CR)is found in non-cardioembolic ischemic stroke (NCIS) patients. However, it is still largely unknown how to identify CR in NCIS patients by laboratory and genetic characteristics.

Methods

A total of 95 patients with acute NCIS were recruited. Phosphorylation of the vasodilator stimulated phosphoprotein (VASP) was detected using flow cytometry, and genes(CYP2C19,CYP3A4) were detected using the Sanger method. The baseline of platelet reactivity index (BPRI) before clopidogrel treatment and the platelet reactivity index with clopidogrel treatment (CPRI) for 7 days were measured. Laboratory clopidogrel resistance (LCR) was defined as CPRI of ≥ 50%.Clinical clopidogrel resistance (CCR) was defined as the presence of progressive stroke during hospitalization, stroke recurrence or occurrence of other ischemic vascular events within 6 months.

Results

The incidence of LCR was 41.05% and 18.95% developed CCR. The incidence of LCR was significantly higher in GA/AA patients with CYP2C19 (681G > A) (χ2 = 11.16, P = 0.001) and CYP2C19 (636G > A) (χ2 = 4.829, P = 0.028) than in wildtype GG patients. CYP2C19 (681G > A) (OR 6.272, 95%CI 2.162,18.199,P = 0.001) and CYP2C19 (636G > A) (OR: 5.625,95%CI 1.439, 21.583,P = 0.013) were risk factors for LCR. patients with LCR were more likely to develop CCR (χ2 = 6.021, P = 0.014). The probability of CCR was markedly increased in GA/AA patients with CYP2C19 (681G > A) (χ2 = 10.341, P = 0.001). We identified CYP2C19 (681G > A) (OR 7.814, 95%CI 1.816, 33.618 P = 0.006), Essen score (OR 8.351, 95%CI 1.848, 37.745 P = 0.006), and LCR (OR 5.881, 95%CI 1.373, 25.192, P = 0.017) as risk factors for CCR.

Conclusion

In clinical practice,LCR and CYP2C19 gene polymorphism should be assessed in NCIS patients receiving clopidogrel treatment.The Chinese Clinical Trial Registry number: ChiCTR-ONC-13003406     

Influence of cytochrome 2C19 allelic variants on on-treatment platelet reactivity evaluated by five different platelet function tests

Background

The antiplatelet effect of clopidogrel has been linked to cytochrome P450 2C19 (CYP2C19) carrier status. The presence of loss of function and gain of function variants were found to have a gene-dose effect on clopidogrel metabolism. However, genotyping is only one aspect of predicting response to clopidogrel and several platelet function tests are available to measure platelet response.Patients and methodsWe studied the influence of CYP2C19 allelic variants on on-treatment platelet reactivity as assessed by light transmission aggregometry (LTA), the VerifyNow P2Y12 assay, the VASP assay, multiple electrode aggregometry (MEA), and the Impact-R in 288 patients after stenting for cardiovascular disease. Allelic variants of CYP2C19 were determined with the Infiniti® CYP450 2C19 + assay and categorized into four metabolizer states (ultrarapid, extensive, intermediate, poor).

Results

Platelet reactivity increased linearly from ultrarapid to poor metabolizers using the VerifyNow P2Y12 assay (P = 0.04), the VASP assay (P = 0.02) and the Impact-R (P = 0.04). The proportion of patients with high on-treatment residual platelet reactivity (HRPR) identified by LTA, the VerifyNow P2Y12 assay and the VASP assay increased when the metabolizer status decreased, while no such relationship could be identified for results of MEA and Impact-R. The presence of loss of function variants (*2/*2, *2-8*/wt, *2/*17) was an independent predictor of HRPR in LTA and the VASP assay while it did not reach statistical significance in the VerifyNow P2Y12 assay, MEA, and the Impact-R.

Conclusion

Depending on the type of platelet function test differences in the association of on-treatment platelet reactivity with CYP2C19 carrier status are observed.     

Relationship Between ABCB1 Polymorphisms,Thromboelastography and Risk of Bleeding Events in Clopidogrel-Treated Patients With ST-Elevation Myocardial Infarction

Introduction

This study sought to investigate the relationship of polymorphisms in ABCB1 and the predictive value of thromboelastography (TEG) on bleeding risk in clopidogrel-treated patients with ST-elevation myocardial infarction (STEMI).

Methods

467 consecutive patients with STEMI undergoing percutaneous coronary intervention (PCI) were enrolled. Twenty tag single nucleotide polymorphisms (SNPs) selected from ABCB1 gene and CYP2C19*2, *3, *17 were detected by the ligase detection reaction. Platelet reactivity was assessed by TEG. The follow-up period was 12 months.

Results

By receiver operating characteristic curve analysis, the TEG platelet mapping assay value of ADP inhibition had the best predictive value of bleeding academic research consortium definition (BARC) ≥ 3b bleedings, yielding an area under the curve (AUC) of 0.707 (95% CI 0.662-0.749, p = 0.009; cut-off value > 93.4%). ADP inhibition can also predict BARC ≥ 3 bleedings with an AUC of 0.594 (95% CI 0.546-0.640, p = 0.05; cut-off value > 92.5%). After adjustment for established risk factors of bleeding including the gain of function CYP2C19*17 allele, age, female gender, renal function, the multivariable logistic regression model demonstrated that ADP inhibition > 92.5% (OR 2.247, 95%CI 1.082-4.665, P = 0.03), carriage of rs1045642 (OR 2.943, 95%CI 1.195-7.247, P = 0.019) and rs7779562 (OR 0.453, 95%CI 0.219-0.936, P = 0.032) were independent predictors of BARC ≥ 3 bleedings. These associations were validated in a second cohort of 504 STEMI patients.

Conclusions

In STEMI patients treated with clopidogrel after PCI, the ABCB1 tag SNP rs1045642 is associated with higher risk of bleedings while rs7779562 is associated with lower bleeding risk, and ADP inhibition in TEG has a predictive value of bleedings.     

Genetic determinants of acenocoumarol and warfarin maintenance dose requirements in Slavic population: A potential role of CYP4F2 and GGCX polymorphisms

Introduction

VKORC1 and cytochrome CYP2C9 genetic variants contribute largely to inter-individual variations in vitamin K antagonists (VKAs) dose requirements. Cytochrome P450 4 F2 isoform (CYP4F2), gamma-glutamyl carboxylase (GGCX) and apolipoprotein E (APOE) polymorphisms have been suggested to be of minor significance.

Materials and Methods

We sought to assess the impact of those polymorphisms on dose requirements in Central-Eastern European cohort of 479 patients receiving acenocoumarol (n = 260) or warfarin (n = 219).

Results

There were no differences between the acenocoumarol and warfarin groups with regard to the gender, age, body mass index and international normalized ratio. The VKORC1 c.-1639A allele carriers required a lower dose of acenocoumarol and warfarin than the non-carriers (28.0 [21.0–35.0] vs. 42.0 [28.0–56.0] mg/week, p < 0.0001; 35.0 [28.0–52.0] vs. 52.0 [35.0–70.0] mg/week, p = 0.0001, respectively). Carriers of *2 and/or *3 variant alleles for CYP2C9 also required a lower dose of warfarin as compared with *1*1 carriers (35.0 [31.5–52.5] vs. 43.8 [35.0–60.2] mg/week, p = 0.02; 35.0 [23.5–35.0] vs. 43.8 [35.0-60.2] mg/week, p < 0.0001, respectively). Similarly, possession of G allele of GGCX c.2084 + 45 polymorphism was associated with lower warfarin dose (35.0 [26.3–39.2] vs. 45.5 [35.0–65.1] mg/week, p = 0.03). No effect of CYP2C9*2,-*3 and GGCX c.2084 + 45G > C polymorphisms on acenocoumarol dosage was observed. Interestingly, carriers of CYP4F2 c.1297A variant required a higher dose of acenocoumarol and warfarin than non-carriers (43.8 [35.0–60.2] vs. 35.0 [35.0–52.5] mg/week, p = 0.01; 35.0 [28.0–52.5] vs. 28.0 [28.0–42.0] mg/week, p = 0.05).

Conclusions

We have shown for the first time, that besides VKORC1 and CYP2C9 genetic variants, the CYP4F2 c.1297A and GGCX c.2084 + 45G have a moderate effect on VKAs dose requirements in Slavic population from Central-Eastern Europe.     

Influence of CYP2C9 polymorphism and phenytoin co-administration on acenocoumarol dose in patients with cerebral venous thrombosis

Background

The study aimed at evaluating the contribution of genetic variations in the drug metabolizing enzyme, CYP2C9, and the influence of co-medication with the antiepileptic drug, phenytoin, to variability in acenocoumarol response, in patients with cerebral venous thrombosis (CVT).

Methods

476 acenocoumarol-treated CVT patients (153 males and 323 females) were genotyped for CYP2C9*2 and CYP2C9*3 polymorphisms by PCR-RFLP method. Mean acenocoumarol dose required for achieving and maintaining a stable international normalized ratio (INR) was calculated for different genotypes. The effect of co-administration with phenytoin was determined.

Results

Genotype distributions of CYP2C9 were as follows: 83%CYP2C9*1/*1, 8.6%CYP2C9*1/*3, 5.9%CYP2C9*1/*2, 1.9%CYP2C9*3/*3, 0.4%CYP2C9*2/*3 and 0.2%CYP2C9*2/*2. During the initiation phase of anticoagulation the CYP2C9*2 allele was independently associated with low acenocoumarol dose requirement (Adjusted OR 5.38; 95%CI 1.65-17.49; p = 0.005). Similarly, the adjusted odds ratio for requiring a low dose during the induction phase in patients bearing the CYP2C9*3 allele was 12.79 (95%CI 4.74-34.57; p < 0.0001). During the maintenance phase, CYP2C9*2 and CYP2C9*3 alleles were associated with 19-fold (Adjusted OR 19.67; 95%CI 2.46-157.19; p = 0.005) and 11.9-fold odds (Adjusted OR 11.98; 95%CI 2.61-55.08; p = 0.001) of requiring a low dose. Clinical covariates such as age, alcohol consumption, postpartum state and oral contraceptive intake also influenced acenocoumarol dosage. Co-medication with phenytoin was associated with lower dose requirement across genotypes during the initiation phase. However, during the maintenance phase, phenytoin-treated patients of all genotypes required higher doses of acenocoumarol.

Conclusion

This study emphasizes the fact that polymorphisms in CYP2C9 gene and co-medication with phenytoin alter the anticoagulant effect of acenocoumarol.     

Impact of the proton pump inhibitors and CYP2C19*2 polymorphism on platelet response to clopidogrel as assessed by four platelet function assays

Background

Previous studies suggested a possible negative interference of proton pump inhibitors (PPIs) on clopidogrel’s antiplatelet effect because of the competitive inhibition of the CYP 2C19 isoenzyme. Moreover, carriers of the loss-of-function allele of CYP2C19 polymorphism (CYP2C19*2) display significantly lower responses to clopidogrel. In this study, we investigated the association between CYP2C19*2 genotype, PPI intake and clopidogrel resistance in patients with coronary artery disease (CAD) and their effect on clinical outcome.

Methods

We recruited 95 patients with CAD receiving chronic clopidogrel therapy in combination with aspirin. Platelet reactivity was simultaneously assessed by INNOVANCE PFA-100 P2Y, ADP-induced light transmission aggregometry (LTA), flow-cytometric vasodilator-stimulated phosphoprotein (VASP)-phosphorylation assay and multiple electrode aggregometry (Multiplate). Cardiovascular outcomes were recorded during 1-year follow-up period.

Results

Only platelet reactivity assessed by measuring platelet phosphorylated-VASP demonstrated a significant higher platelet reactivity in carriers of CYP2C19*2 (p = 0.023). The other methods displayed higher - but not statistically significant - platelet reactivity in patients carrying the CYP2C19*2 variant as compared with non-carriers. Patients on PPIs demonstrated almost similar suppression of platelet reactivity in comparison with those not treated with PPIs by all platelet function assays. In logistic regression analysis none of the platelet function assays measurements were related with clinical outcomes. Similarly neither CYP2C19*2 genetic variant nor PPI treatment were associated with adverse clinical events.

Conclusions

PPI co-administration did not influence clopidogrel’s antiplatelet effect on laboratory testing by all platelet function assays used. On the contrary, patients carrying CYP2C19*2 genotype had significantly higher residual platelet reactivity as estimated by VASP-phosphorylation assay.     

Impact of P2Y12-ADP receptor polymorphism on the efficacy of clopidogrel dose-adjustment according to platelet reactivity monitoring in coronary artery disease patients

Introduction

High on-treatment platelet reactivity (HTPR) after clopidogrel loading dose (LD) is associated with a high risk of thrombotic events after percutaneous coronary intervention(PCI). We have demonstrated that HTPR could be overcome in the majority of cases using LD adjustment resulting in an improved clinical outcome. However this strategy failed in nearly 10% of patients with HTPR. We aimed to determine if P2Y12-ADP receptor polymorphisms were associated with failed dose adjustment.

Materiel and method

Forty-three patients undergoing PCI were included in this prospective study. A VASP index ≥ 50% after a 600 mg LD of clopidogrel defined HTPR. Dose adjustment was performed according to PR monitoring to reach a VASP index < 50%. Genetic polymorphism of the P2Y12-ADP receptor was determined by direct sequencing.

Results

Patients with successful dose-adjustment (SDA) (n = 33) and failed (FDA) (n = 10) dose-adjustment groups were compared. The 2 groups were similar in terms of cardiovascular risk factors including diabetes mellitus (SDA vs FDA: 42 vs 20%; p = 0.3). The prevalence of the H2 allele of the P2Y12-ADP receptor was also similar between the 2 groups (p = 0.3). The H2 allele was found in 6 patients which are all included in the SDA group. After the first 600 mg loading dose of clopidogrel, patients carrying at least one H2 allele had similar VASP index compared to those carrying two copies of the wild type allele (H1) (SDA vs FDA: 44.9 ± 14.9 vs 43.5 ± 10%; p = 0.8).

Conclusion

The present study suggests that the H2 allele of the P2Y12-ADP receptor is not involved in clopidogrel failed dose adjustment according to platelet reactivity monitoring.     

Association between adiponectin gene polymorphisms and coronary artery disease across different populations

Objective

Many studies have suggested that adiponectin gene might be involved in the development of coronary artery disease (CAD). However, the results have been inconsistent. In this study, the authors performed a meta-analysis to assess the associations of + 45T/G, + 276G/T and − 11377C/G polymorphisms in adiponectin gene with CAD susceptibility.

Methods

Published literature from PubMed and EMBASE databases were searched. Pooled odds ratio (OR) and corresponding 95% confidence interval (CI) were calculated using fixed- or random-effects model.

Results

Sixteen studies (4394 cases / 8187 controls) for + 45T/G polymorphism, fifteen studies (3569 cases / 7463 controls) for + 276G/T polymorphism, and thirteen studies (3531 cases / 7072 controls) for − 11377C/G polymorphism were included in the meta-analysis. The overall results showed that there was a statistically significant association between − 11377C/G polymorphism and CAD (G vs. C: OR = 1.15, 95%CI 1.07-1.24).Similar results were observed among European (G vs. C: OR = 1.11, 95%CI 1.02-1.20) and East Asian populations (G vs. C: OR = 1.27, 95%CI 1.11-1.45). However, no significant association was found for + 45T/G or + 276G/T polymorphism with CAD susceptibility.

Conclusions

The meta-analysis indicated the significant association of − 11377C/G polymorphism, but not + 45T/G or + 276G/T polymorphism, with CAD susceptibility. However, large-scale studies with the consideration of gene-gene and gene-environment interactions should be conducted to investigate the associations in future.     

ABCB1 C3435T polymorphism and risk of adverse clinical events in clopidogrel treated patients: a meta-analysis

Introduction

The ABCB1 C3435T polymorphism limits oral bioavailability of clopidogrel and may influence prognosis of patients treated with clopidogrel. Several studies have examined the association between the C3435T polymorphism and risk of adverse clinical events in clopidogrel treated patients, but the results were inconsistent. To assess the role of the C3435T polymorphism in the impact on clinical outcomes, a meta-analysis was conducted.

Methods

6 studies with 10,153 subjects were included in this meta-analysis. Fixed- or random-effects model was chosen according to heterogeneity. Publication bias was evaluated by fail-safe numbers.

Results

The association of the C3435T polymorphism with risk of overall recurrent ischemic events in clopidogrel treated patients was not statistically significant for all genetic models (OR = 1.13, 95%CI: 0.78-1.64, P = 0.51; OR = 1.15, 95%CI: 0.99-1.33, P = 0.07; OR = 1.19, 95%CI: 0.81-1.76, P = 0.37). Significant association was identified between the C3435T polymorphism and risk of short-term recurrent ischemic events (OR = 1.55, 95% CI: 1.09-2.20, P = 0.01; OR = 1.41, 95% CI: 1.06-1.87, P = 0.02; OR = 1.77, 95% CI: 1.19-2.63, P = 0.005). No statistically significant association between the C3435T polymorphism and stent thrombosis (OR = 0.79, 95% CI: 0.47-1.32, P = 0.37) or bleeding (OR = 0.98, 95% CI: 0.79-1.21, P = 0.82) was identified. The results may be affected by publication bias.

Conclusions

This meta-analysis failed to show an association between the ABCB1 C3435T polymorphism and risk of overall recurrent ischemic events, stent thrombosis or bleeding in clopidogrel treated patients. However, the association between TT homozygotes of the C3435T polymorphism and risk of short-term recurrent ischemic events may exist, but needs more studies to confirm.     

A case-control study provides evidence of association for a common SNP rs974819 in PDGFD to coronary heart disease and suggests a sex-dependent effect

Introduction

Peden et al. have revealed a significant association between four new risk loci and coronary heart disease (CHD) in Europeans and South Asians. The goal of this study is to evaluate the contribution of these genetic loci to CHD risk in Han Chinese.

Methods

We recruited 161 CHD patients and 112 controls proved by angiography originated from Ningbo in the Eastern China, and performed a case-control association study of the four significant SNPs.

Results

Among the four tested SNPs, we found a significant association of rs974819 in PDGFD gene with CHD (allele p = 0.04; OR = 1.45, 95% CI = 1.02 - 2.08) and the allele A/G of rs974819 shows significant difference in females (allele p = 0.04; OR = 1.83, 95% CI = 1.01 - 3.31). A further meta-analysis showed that rs974819 of PDGFD gene was significantly associated with an increasing risk of CHD (OR = 1.08, 95% CI = 1.05 - 1.11) in both Europeans and South Asians including Han Chinese.

Conclusions

Our findings suggests that rs974819 of PDGFD is also a CHD risk factor in Han Chinese. In addition, it presents a sex-dependent genetic effect.     

Genetic determinants of response to aspirin: appraisal of 4 candidate genes

Introduction

Intersubject variability in platelet response to aspirin could be related to genetic factors that regulate platelet enzymes or receptors. This study evaluates the impact of the selected polymorphisms in the COX-1 gene, the CYP5A1 gene, the P2RY1 receptor gene, and the GPIIbIIIa receptor gene on platelet response to aspirin and risk of suffering from major adverse cardiovascular and cerebrovascular events (MACCE).

Materials and methods

192 Caucasian patients with stable coronary artery disease treated with daily aspirin were recruited and followed for 3 years. Platelet aggregation was measured by light transmission aggregometry with arachidonic acid (1.6 mM) and adenosine diphosphate (5, 10 or 20 μM) used as agonists. Genotyping was performed by standard PCR methods.

Results

Arachidonic acid-induced platelet aggregation was unaffected by the COX-1 22C/T and by the Pl^A1/A2 polymorphisms. However, carriers of the 1622 G/G genotype of the P2RY1 gene had significantly higher levels of arachidonic acid-induced platelet aggregation compared with non-carriers (AA 2.0%, AG 2.0% vs. GG 9.0%, p = 0.047). Carrying the 1622 G/G genotype increased the risk of inadequate platelet response to aspirin, defined as arachidonic acid-induced aggregation ≥ 20%, by a factor of 8.5 (1.4 - 53.3, p = 0.022) and the risk of 3-year MACCE by a factor of 7 (1.4 - 34.7, p = 0.017).

Conclusion

The 1622A/G mutation of the P2RY1 gene could contribute to inadequate platelet response to aspirin and is associated with an increased risk of suffering from MACCE.     

Chronic kidney disease status modifies the association of CYP2C19 polymorphism in predicting clinical outcomes following coronary stent implantation

Introduction

There is some controversy regarding the effect of CYP2C19 polymorphism on clinical outcome in patients with dual antiplatelet therapy. Chronic kidney disease (CKD) is associated with increased risk of cardiovascular event, but the association between the possession of CYP2C19 loss-of-function (LOF) alleles and clinical outcome according to the presence of CKD is poorly understood. The aim of this study was to investigate whether CKD status modifies the association of CYP2C19 polymorphism in predicting outcomes in a prospective cohort study.

Material and Methods

We enrolled 331 patients following coronary stent implantation. Patients were divided into two groups: CKD (n = 154) and non-CKD (n = 177). Platelet reactivity and CYP2C19 polymorphism were examined. The subjects were further divided into two groups according to the possession of CYP2C19 LOF alleles: carriers and non-carriers. Patients were followed up and clinical events were evaluated according to CKD and carrier status.

Results

The proportion of high platelet reactivity was significantly higher in carriers than in non-carriers in both CKD (42.4% versus 21.7%; P = 0.016) and non-CKD groups (34.3% versus 3.7%; P < 0.001). In the non-CKD group alone, the incidence of cardiovascular events was significantly higher in carriers than in non-carriers (13.7% versus 1.7%; P = 0.013). Kaplan-Meier analysis demonstrated a significantly higher probability of cardiovascular events in carriers than in non-carriers in the non-CKD group (log-rank test: P = 0.013) and there was no significant difference in the CKD group (log-rank test: P = 0.591). Multivariate analysis identified carriers as an independent predictor of cardiovascular events only in the non-CKD group alone (hazard ratio: 8.048; 95% confidence interval: 1.066 to 60.757; P = 0.043).

Conclusions

CYP2C19 polymorphism significantly correlates with clinical outcome in non-CKD patients, and CKD status modifies the association of CYP2C19 polymorphism in predicting clinical outcomes following coronary stent implantation.     

Impact of CYP2C19 polymorphism on clinical outcome following coronary stenting is more important in non-diabetic than diabetic patients

Objective

The aim of this study was to examine the impact of CYP2C19 genotype on clinical outcome in coronary artery disease (CAD) patients with or without diabetes mellitus (DM).

Methods

CYP2C19 polymorphism and DM are associated with increased risk of cardiovascular events during antiplatelet therapy following stent implantation. Platelet reactivity during clopidogrel therapy and CYP2C19 polymorphism were measured in 519 CAD patients (males 70%, age 69 years) treated with stent placement. Patients were divided into two groups; DM (n = 249), and non-DM (n = 270), and clinical events were evaluated according to the carrier state, which included at least one CYP2C19 loss-of-function allele.

Results

The level of platelet reactivity and incidence of cardiovascular events were significantly different between Carriers and non-Carriers of the non-DM (platelet reactivity: 4501 +/− 1668 versus 3691 +/− 1714AUmin, P < 0.01; events, 32/178 versus 2/92, P < 0.01, respectively), however, there was no difference in clinical outcome in the DM group (events, 34/168 versus 14/81, respectively, P = 0.57). Multivariate analysis identified CYP2C19 loss-of-function allele carriage as an independent predictor of cardiovascular events in non-DM, but not in DM (non-DM, HR 7.180, 95% CI, 1.701 to 30.298, P = 0.007; DM, HR 1.374, 95% CI, 0.394 to 4.792, P = 0.618).

Conclusion

The impact of CYP2C19 polymorphism on clinical outcome seems to be more significant in non-DM compared with DM in patients with coronary stents.     

Association of F11 polymorphism rs2289252 with deep vein thrombosis and related phenotypes in population of Latvia

Introduction

Deep vein thrombosis (DVT) has a strong inherited predisposition that is partly explained by the strong genetic risk factors such as mutations in factor V, prothrombin, antithrombin III, protein C and S genes. Only recently the first GWAS have been performed on DVT resulting in discovery of novel genetic variants, however, the information on the common polymorphisms predisposing to the risk of DVT is still scarce.

Materials and Methods

Here we selected six SNPs (rs5361 in SELE, rs2066865 in FGG, rs2227589 in SERPINC1, rs1613662 in GP6, rs13146272 in CYP4V2, rs2289252 in F11) reported to be associated with venous thrombosis conditions and studied the association of these common variants in selected case (n = 177) and control (n = 235) groups from population of Latvia. Genotyping was performed using TaqMan hybridization probe SNP genotyping assay.

Results

Patients with DVT had a significantly higher frequency of F11 rs2289252 polymorphism (p = 0.001; OR [95%CI] = 1.61 [1.20-2.14]). When stratified by recurrence of DVT the tendency was observed that the same SNP had higher OR value in group of DVT patients with repeated episodes of DVT compared to patients with single DVT episode (p = 0.009; OR [95%CI] = 2.27[1.22-4.21] and p = 0.009; OR [95%CI] = 1.52[1.11-2.08] respectively), but due to limited group of cases this finding should be replicated.

Conclusion

We conclude that F11 gene variant rs2289252 contribute to inherited forms of DVT incidence and correlation of other analysed SNPs should be explored in populations with greater sample size and associated with various thrombosis related traits.     

Thrombophilic screening in young patients (< 40 years) with idiopathic ischemic stroke: a controlled study

Introduction

Despite extensive clinical and laboratory investigations, the etiology of ischemic stroke remains unknown in approximately one third of patients.

Materials and Methods

Thirty-four consecutive patients less than 40 years old (Males 13, Females 21, mean age 26.6 years, range 2-39) with documented ischemic stroke underwent, one year after the acute event, laboratory evaluation of antithrombin, protein C, free and total protein S, activated protein C resistance, fibrinogen, factor VII:C, homocysteine levels and antiphospholipid antibodies (APA). Moreover, prevalence of F5 R506Q, F2 G2021A and homozygosis for thermolabile variant C677T of the methylenetetrahydrofolate reductase (MTHFR) were also evaluated and compared to the results obtained in 120 normal controls.

Results

Antithrombin and protein C levels resulted normal in all cases. One patient (2.9%) showed free protein S deficiency and 3 patients (8.8%) had activated protein C resistance. Homocysteine levels above 15 μmol/L were found in one patient (2.9%). APA were found in 21 patients (61.7%) and in only 2 out of 120 (1.66%) controls (OR = 95.31; 95% C.I.: 18.22-667.81). The multivariate analysis selected that the presence of APA was significantly associated with an increased risk of stroke (OR = 156.60; 95% C.I.: 25.99-943.47) in this cohort of patients. The combination between APA and cardiovascular risk factors determined a risk of 29-fold (OR = 29.31; 95% CI: 3.28-261.69).

Discussion

Our data suggest that the presence of APA is associated with an increased risk of idiopathic ischemic stroke in young patients. Furthermore, also the combination of APA and cardiovascular risk factors is significantly associated with development of idiopathic ischemic stroke.     

Gender differences in the effects of peroxisome proliferator-activated receptor γ2 gene polymorphisms on metabolic adversity in patients with schizophrenia or schizoaffective disorder

Objective

Metabolic syndrome (MS) is a major health problem in schizophrenic patients. Peroxisome proliferator-activated receptor γ2 (PPARγ2) is one of the candidate genes responsible for the liability to metabolic problems. In this study, we investigated the effect of the PPARγ2 gene Pro12Ala and C161T polymorphisms on metabolic adversities in patients with schizophrenia or schizoaffective disorder.

Methods

Metabolic profiles and PPARγ2 gene polymorphisms were determined in 600 patients (309 men and 291 women) with a clinical diagnosis of schizophrenia or schizoaffective disorder. Metabolic indices and components of MS were compared between patients with different Pro12Ala or C161T genotypes.

Results

In the whole population, the allele frequency of 12Ala and 161T was 4.4% and 24.7% respectively. Both polymorphisms had no significant effect on obesity or metabolic-related traits. However, following gender stratification of the data, we found female 12Ala allele carriers were at greater risk of developing abdominal obesity (OR = 4.0, 95% CI = 1.1-14.2, p = 0.04) and hypertension (OR = 2.9, 95% CI = 1.2-7.4, p = 0.02) than female 12Ala allele non-carriers. Male 161T allele carriers had lower insulin levels (p = 0.02) and lower high-density lipoprotein cholesterol (HDL-C) (p = 0.05) levels than male 161T allele non-carriers. Moreover, female 161T allele carriers had higher body weight (p = 0.04), waist circumference (p = 0.05), and systolic blood pressure (p = 0.01), and were at greater risk of developing hypertension (OR = 2.0, 95% CI = 1.1-3.5, p = 0.02). Haplotype analyses showed that PPARγ2 gene polymorphisms were significantly associated with HDL-C level in men and blood pressure in women.

Conclusions

We did not find an association of PPARγ2 gene polymorphisms with MS or obesity in our schizophrenia sample. But further analyses by gender stratification revealed gender-specific differences in the effect of different PPARγ2 genotypes on certain metabolic adversities in these patients.     

Comparative performance of warfarin pharmacogenetic algorithms in Chinese patients

Introduction

Multiple warfarin pharmacogenetic algorithms have been confirmed to predict warfarin dose more accurately than clinical algorithm or the fixed-dose approach. However, their performance has never been objectively evaluated in patients under low intensity warfarin anticoagulation, which is optimal for prevention of thromboembolism in Asian patients.

Material and methods

We sought to compare the performances of 8 eligible pharmacogenetic algorithms in a cohort of Chinese patients (n = 282) under low intensity warfarin anticoagulation with target international normalized ratio (INR) ranged from 1.6 to 2.5. The performance of each algorithm was evaluated by calculating the percentage of patients whose predicted dose fell within 20% of their actual therapeutic dose (percentage within 20%), and the mean absolute error (MAE) between each predicted dose and actual stable dose.

Results

In the entire cohort, the pharmacogenetic algorithms could predict warfarin dose with the average MAE of 0.87 ± 0.17 mg/day (0.73-1.17 mg/day), and the average percentage within 20% of 43.8% ± 8.1% (29.1% - 52.1%). By pairwise comparison, warfarin dose prediction was significantly more accurate with the algorithms derived from Asian patients (48.6% - 50.0%) than those from Caucasian patients (29.1% - 39.7%; odds ratio [OR]: 1.61-3.36, p ≤ 0.02). Algorithms with additional covariates of INR values or CYP4F2*3 performed better than those without the covariates (adding INR: OR: 1.71 (1.08-2.72), p = 0.029; adding CYP4F2*3: OR: 2.67(1.41-5.05), p = 0.004). When the patients were stratified according to the dose range, the algorithms from Caucasian and racially mixed populations tended to perform better in higher dose group (≥ 4.5 mg/day), and algorithms from Asian populations performed better in intermediate dose group (1.5-4.5 mg/day). None of the algorithms performed well in lower dose group (≤ 1.5 mg/day).

Conclusions

No eligible pharmacogenetic algorithm could perform the best for all dosing range in the Chinese patients under low intensity warfarin anticoagulation. Construction of a refinement pharmacogenetic algorithm integrating 3 genotypes (CYP2C9, VKORC1 and CYP4F2) and INR data should be warranted to improve the warfarin dose prediction in such patients.