Betti Giusti

Reduced-Function CYP2C19 Genotype and Risk of Adverse Clinical Outcomes Among Patients Treated With Clopidogrel Predominantly for PCI: A Meta-Analysis

CONTENT Clopidogrel, one of the most commonly prescribed medications, is a prodrug requiring CYP450 biotransformation. Data suggest its pharmacologic effect varies based on CYP2C19 genotype, but there is uncertainty regarding the clinical risk imparted by specific genotypes. OBJECTIVE To define the risk of major adverse cardiovascular outcomes among carriers of 1 (≈ 26% prevalence in whites) and carriers of 2 (≈ 2% prevalence in whites) reduced-function CYP2C19 genetic variants in patients treated with clopidogrel. DATA SOURCES AND STUDY SELECTION A literature search was conducted (January 2000-August 2010) in MEDLINE, Cochrane Database of Systematic Reviews, and EMBASE. Genetic studies were included in which clopidogrel was initiated in predominantly invasively managed patients in a manner consistent with the current guideline recommendations and in which clinical outcomes were ascertained. DATA EXTRACTION Investigators from 9 studies evaluating CYP2C19 genotype and clinical outcomes in patients treated with clopidogrel contributed the relevant hazard ratios (HRs) and 95% confidence intervals (CIs) for specific cardiovascular outcomes by genotype. RESULTS Among 9685 patients (91.3% who underwent percutaneous coronary intervention and 54.5% who had an acute coronary syndrome), 863 experienced the composite end point of cardiovascular death, myocardial infarction, or stroke; and 84 patients had stent thrombosis among the 5894 evaluated for such. Overall, 71.5% were noncarriers, 26.3% had 1 reduced-function CYP2C19 allele, and 2.2% had 2 reduced-function CYP2C19 alleles. A significantly increased risk of the composite end point was evident in both carriers of 1 (HR, 1.55; 95% CI, 1.11-2.17; P = .01) and 2 (HR, 1.76; 95% CI, 1.24-2.50; P = .002) reduced-function CYP2C19 alleles, as compared with noncarriers. Similarly, there was a significantly increased risk of stent thrombosis in both carriers of 1 (HR, 2.67; 95% CI, 1.69-4.22; P < .0001) and 2 (HR, 3.97; 95% CI, 1.75-9.02; P = .001) CYP2C19 reduced-function alleles, as compared with noncarriers. CONCLUSION Among patients treated with clopidogrel for percutaneous coronary intervention, carriage of even 1 reduced-function CYP2C19 allele appears to be associated with a significantly increased risk of major adverse cardiovascular events, particularly stent thrombosis.

Cardiovascular Death and Nonfatal Myocardial Infarction in Acute Coronary Syndrome Patients Receiving Coronary Stenting Are Predicted by Residual Platelet Reactivity to ADP Detected by a Point-of-Care Assay A 12-Month Follow-Up

Background— The clinical impact of platelet aggregation assessed by point-of-care assays is unknown. We sought to evaluate whether high residual platelet reactivity (RPR) to ADP during clopidogrel therapy, measured by a point-of-care assay, predicts adverse clinical events in acute coronary syndrome patients undergoing percutaneous coronary intervention. Methods and Results— We used the VerifyNow P2Y12 assay (Accumetrics Inc, San Diego, Calif) to determine RPR to ADP in 683 patients with acute coronary syndrome undergoing dual-antiplatelet therapy who underwent percutaneous coronary intervention with bare-metal or drug-eluting stent implantation. All patients received a single 600-mg clopidogrel loading dose followed by 75 mg of clopidogrel daily and 100 to 325 mg of aspirin daily. The end points of the study at follow-up of 12 months were cardiovascular death, nonfatal myocardial infarction (MI), and target-vessel revascularization. At a 12-month follow-up, we found 51 ischemic events (24 cardiovascular deaths [3.5%], 27 nonfatal MIs [3.9%]) and 40 target-vessel revascularizations (5.8%). By receiver operating characteristic curve (ROC) analysis, the optimal cutoff value in predicting 12-month cardiovascular death and nonfatal MI was P2Y12 reaction unit values ≥240. RPR, defined in the presence of P2Y12 reaction unit values above this cutoff, was found to be a significant and independent predictor of cardiovascular death and nonfatal MI in a model that adjusted for cardiovascular risk factors, renal failure, reduced left ventricular ejection fraction, multivessel disease, total stent length, bifurcation lesions, number of lesions treated, type of stent, and use of glycoprotein IIb/IIIa inhibitors (cardiovascular death: hazard ratio 2.55, 95% CI 1.08 to 6.07, P=0.034; nonfatal MI: hazard ratio 3.36, 95% CI 1.49 to 7.58, P=0.004). No significant association was found between high RPR and the risk of target-vessel revascularization. Conclusions— RPR to ADP with clopidogrel therapy, measured by the point-of-care assay VerifyNow P2Y12, is able to detect acute coronary syndrome patients at risk of 12-month cardiovascular death and nonfatal MI. The optimal cutoff value was identified as being 240 P2Y12 reaction units.

High Residual Platelet Reactivity After Clopidogrel Loading and Long-term Cardiovascular Events Among Patients With Acute Coronary Syndromes Undergoing PCI

CONTEXT High residual platelet reactivity (HRPR) in patients receiving clopidogrel has been associated with high risk of ischemic events after percutaneous coronary intervention (PCI). OBJECTIVE To test the hypothesis that HRPR after clopidogrel loading is an independent prognostic marker of risk of long-term thrombotic events in patients with acute coronary syndromes (ACS) undergoing an invasive procedure and antithrombotic treatment adjusted according to the results of platelet function tests. DESIGN, SETTING, AND PATIENTS Prospective, observational, referral center cohort study of 1789 consecutive patients with ACS undergoing PCI from April 2005 to April 2009 at the Division of Cardiology of Careggi Hospital, Florence, Italy, in whom platelet reactivity was prospectively assessed by light transmittance aggregometry. INTERVENTIONS All patients received 325 mg of aspirin and a loading dose of 600 mg of clopidogrel followed by a maintenance dosage of 325 mg/d of aspirin and 75 mg/d of clopidogrel for at least 6 months. Patients with HRPR as assessed by adenosine diphosphate test (≥70% platelet aggregation) received an increased dose of clopidogrel (150-300 mg/d) or switched to ticlopidine (500-1000 mg/d) under adenosine diphosphate test guidance. MAIN OUTCOME MEASURES The primary end point was a composite of cardiac death, myocardial infarction, any urgent coronary revascularization, and stroke at 2-year follow-up. Secondary end points were stent thrombosis and each component of the primary end point. RESULTS The primary end point event rate was 14.6% (36/247) in patients with HRPR and 8.7% (132/1525) in patients with low residual platelet reactivity (absolute risk increase, 5.9%; 95% CI, 1.6%-11.1%; P = .003). Stent thrombosis was higher in the HRPR group compared with the low residual platelet reactivity group (6.1% [15/247] vs 2.9% [44/1525]; absolute risk increase, 3.2%; 95% CI, 0.4%-6.7%; P = .01). By multivariable analysis, HRPR was independently associated with the primary end point (hazard ratio, 1.49; 95% CI, 1.08-2.05; P = .02) and with cardiac mortality (hazard ratio, 1.81; 95% CI, 1.18-2.76; P = .006). CONCLUSION Among patients receiving platelet reactivity-guided antithrombotic medication after PCI, HRPR status was significantly associated with increased risk of ischemic events at short- and long-term follow-up. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT01231035.

Ullrich scleroatonic muscular dystrophy is caused by recessive mutations in collagen type VI

Ullrich syndrome is a recessive congenital muscular dystrophy affecting connective tissue and muscle. The molecular basis is unknown. Reverse transcription–PCR amplification performed on RNA extracted from fibroblasts or muscle of three Ullrich patients followed by heteroduplex analysis displayed heteroduplexes in one of the three genes coding for collagen type VI (COL6). In patient A, we detected a homozygous insertion of a C leading to a premature termination codon in the triple-helical domain of COL6A2 mRNA. Both healthy consanguineous parents were carriers. In patient B, we found a deletion of 28 nucleotides because of an A → G substitution at nucleotide −2 of intron 17 causing the activation of a cryptic acceptor site inside exon 18. The second mutation was an exon skipping because of a G → A substitution at nucleotide −1 of intron 23. Both mutations are present in an affected brother. The first mutation is also present in the healthy mother, whereas the second mutation is carried by their healthy father. In patient C, we found only one mutation so far—the same deletion of 28 nucleotides found in patient B. In this case, it was a de novo mutation, as it is absent in her parents. mRNA and protein analysis of patient B showed very low amounts of COL6A2 mRNA and of COL6. A near total absence of COL6 was demonstrated by immunofluorescence in fibroblasts and muscle. Our results demonstrate that Ullrich syndrome is caused by recessive mutations leading to a severe reduction of COL6.

Cytochrome P450 2C19 loss-of-function polymorphism, but not CYP3A4 IVS10 + 12G/A and P2Y12 T744C polymorphisms, is associated with response variability to dual antiplatelet treatment in high-risk vascular patients.

Objectives The aim of this study was to evaluate the effect of polymorphisms affecting the clopidogrel metabolism (CYP3A4 IVS10+12G/A and CYP2C19*2) and the P2Y12 receptor (P2Y12 T744C) on modulating platelet function in acute coronary syndrome patients on dual antiplatelet treatment. Background Residual platelet reactivity (RPR) phenomenon on antiplatelet therapy requires clarification. P2Y12 T744C, CYP3A4 IVS10+12G/A and, in healthy individuals only, CYP2C19*2 polymorphisms have been investigated; however, the influence on platelet reactivity in a large population of high-risk vascular patients on dual antiplatelet treatment has not yet been elucidated. Methods A total of 1419 acute coronary syndrome patients on dual antiplatelet treatment were studied. Platelet function was evaluated by platelet-rich plasma aggregation. Electronic nanochips and restriction-fragment length polymorphism were used for analysis of polymorphisms. Results Only CYP2C19*2, out of the three investigated polymorphisms, is associated with higher platelet reactivity. Carriers of the *2 allele had significantly higher platelet aggregation values after arachidonic acid (AA; P=0.043), 2 μmol/l adenosine 5′ diphosphate (ADP; P<0.0001) and 10 μmol/l ADP (P=0.001) stimuli. The genotype distribution of CYP2C19*2 polymorphism significantly differed between patients with and without RPR, as evaluated by 10-μmol/l ADP-induced platelet aggregation (P=0.002) and by AA-induced platelet aggregation (P=0.045). At the multivariate linear regression analysis, the CYP2C19*2 polymorphism remained a significant and independent risk factor for dual antiplatelet treatment variability. Conclusions This study demonstrates, for the first time, that the *2 CYP2C19 allele is associated with higher platelet aggregability and RPR in high-risk vascular patients on dual antiplatelet treatment. These findings can have a significant impact on the future design of pharmacogenetic antiaggregant strategies for high-risk vascular patients on dual antiplatelet treatment.

Transient intermittent lymphocyte activation is responsible for the instability of angina.

BackgroundBlood clotting activation is an important component of the inflammatory response; the outbursts of unstable angina are usually associated with increased thrombin formation and coronary mural thrombosis. Methods and ResultsTo investigate 1) whether monocyte activation is responsible for the enhanced thrombin formation during bursts of unstable angina and 2) what mechanism(s) might be responsible for monocyte activation, we studied patients with unstable angina (n=31), stable effort angina (n=23), left endoventricular thrombosis (n=8), and control subjects (n=44), measuring plasma fibrinopeptide A (FPA) levels and the capacity of monocytes to express procoagulant activity (PCA) and of lymphocytes to modulate this expression. Patients with unstable angina and patients with endoventricular thrombosis had significantly (p<0.0001) higher FPA plasma levels than patients with effort angina and control subjects. However, only monocytes from unstable angina patients expressed significantly increased PCA characterized as tissue factor-like activity (units/105 monocytes, median and range; 120, 1.1–463.2 versus 10.8, 0.8–39.1 in control subjects; p<0.0001 versus the other groups). When 14 patients with unstable angina were restudied 8–12 weeks later, they showed neither elevated plasma FPA levels nor monocyte PCA. In unstable angina patients, there was a correlation between FPA and PCA (r=0.56, p<0.001). For expression of PCA by monocytes, both an incubation of at least 2 hours with lymphocytes and direct monocyte-lymphocyte contact were needed. In reconstitution and cross-mixing experiments, only lymphocytes from patients with active unstable angina induced the expression ofPCA by monocytes from both control and patient groups. ConclusionsThe results demonstrate that the increased thrombin formation in unstable angina patients is due to the expression of tissue factor-like activity by activated monocytes. The monocyte activation appears to be a part of a lymphocytic cell-instructed response intermittently triggered by unknown factors.

Clopidogrel non-responsiveness and risk of cardiovascular morbidity: an updated meta-analysis

We performed this meta-analysis to update the clinical evidences on the relation between clopidogrel non-responsiveness and clinical outcomes in patients with coronary artery disease (CAD) who underwent percutaneous coronary intervention. An electronic literature search through MEDLINE, EMBASE, Web of Science, and the Cochrane Library and bibliographies of retrieved articles up to January, 2009 was conducted. Studies were included if they had a cohort prospective design, if they analysed clopidogrel responsiveness in CAD patients in relation to death and/or occurrence of adverse coronary events during follow-up, and if they reported an adequate statistical analysis. Fourteen studies, totalling 4,564 CAD patients followed for a time ranging from 14 days to one year, were included. The cumulative analysis reported that residual platelet reactivity despite clopidogrel treatment was significantly associated with an increased risk of death and/or thrombotic recurrences (odds ratio [OR] 5.67, 95% confidence interval [CI] 2.97 to 10.84; p<0.00001). However, four studies contributed to a consistent heterogeneity of the model and evidenced a significant risk of publication bias, so were excluded from the analysis. This exclusion, however, did not influence the overall result, by confirming the increased risk of cardiovascular recurrences for patients with a poor response to clopidogrel treatment (OR 3.58, 95%CI 2.54 to 5.05; p<0.00001). The present updated meta-analysis documents a significant association between residual platelet reactivity under clopidogrel treatment and recurrent cardiovascular events, so suggesting the relevance of ongoing interventional studies aimed at tailoring the antithrombotic therapy in CAD patients.

Genome-wide Association Study of Vitamin B6, Vitamin B12, Folate, and Homocysteine Blood Concentrations

The B vitamins are components of one-carbon metabolism (OCM) that contribute to DNA synthesis and methylation. Homocysteine, a by-product of OCM, has been associated with coronary heart disease, stroke and neurological disease. To investigate genetic factors that affect circulating vitamin B6, vitamin B12, folate and homocysteine, a genome-wide association analysis was conducted in the InCHIANTI (N = 1175), SardiNIA (N = 1115), and BLSA (N = 640) studies. The top loci were replicated in an independent sample of 687 participants in the Progetto Nutrizione study. Polymorphisms in the ALPL gene (rs4654748, p = 8.30 x 10(-18)) were associated with vitamin B6 and FUT2 (rs602662, [corrected] p = 2.83 x 10(-20)) with vitamin B12 serum levels. The association of MTHFR, a gene consistently associated with homocysteine, was confirmed in this meta-analysis. The ALPL gene likely influences the catabolism of vitamin B6 while FUT2 interferes with absorption of vitamin B12. These findings highlight mechanisms that affect vitamin B6, vitamin B12 and homocysteine serum levels.

Cytochrome P450 2C19 * 2 polymorphism and cardiovascular recurrences in patients taking clopidogrel: a meta-analysis

Several polymorphisms in genes that encode platelet components (receptors or enzymes), or cytochrome P450 enzyme isoforms, involved in clopidogrel metabolism, have been proposed as possible mechanisms for nonresponsiveness to clopidogrel. Among them, a great deal of attention has been focused on the loss-of-function CYP2C19*2 (or 681 G>A) polymorphism. We performed a meta-analysis of all the prospective studies that have been published, which analyze the role of such a polymorphism in recurrent cardiovascular events in patients with coronary artery disease (CAD) being treated with clopidogrel. Studies were searched in MedLine, Embase, Web of Science, The Cochrane Systematic Review Database, Google Scholar and bibliographies of retrieved articles up to January 2010. The principal underlying hypothesis was that the presence of the *2 variant allele of the polymorphism would be associated with an increased risk of clinical recurrence. Data were available for a total of 8043 patients from seven cohort prospective studies, who were followed for a period of time ranging from 6 months to 8.3 years. The summary risk ratios (RRs) for the prospective cohort studies included showed a significant association between the CYP2C19*2 polymorphism and an increased risk of major adverse cardiovascular events in the follow-up (RR: 1.96 (1.14–3.37); P=0.02). When studies evaluating stent thrombosis (n=4) for a total of 4975 patients were considered, the presence of the variant allele was associated with an increased risk of stent thrombosis (RR: 3.82 (2.23–6.54); P=0.0001). The current meta-analysis, carried out on nearly 8000 patients with CAD undergoing clopidogrel treatment, shows that the CYP2C19*2 polymorphism is associated with an increased risk of major adverse cardiovascular events and stent thrombosis.

EXCAVATOR: detecting copy number variants from whole-exome sequencing data.

AbstractWe developed a novel software tool, EXCAVATOR, for the detection of copy number variants (CNVs) from whole-exome sequencing data. EXCAVATOR combines a three-step normalization procedure with a novel heterogeneous hidden Markov model algorithm and a calling method that classifies genomic regions into five copy number states. We validate EXCAVATOR on three datasets and compare the results with three other methods. These analyses show that EXCAVATOR outperforms the other methods and is therefore a valuable tool for the investigation of CNVs in largescale projects, as well as in clinical research and diagnostics. EXCAVATOR is freely available at http://sourceforge.net/projects/excavatortool/.