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Publications (7)27.66 Total impact

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    ABSTRACT: To investigate the impact of genotypes on the basis of the loss-of-function variant CYP2C19*2 and the gain-of-function variant CYP2C19*17 on on-treatment platelet reactivity and on the occurrence of Thrombolysis in Myocardial Infarction (TIMI) major bleedings in 820 clopidogrel-treated patients who underwent elective coronary stenting. On-treatment platelet reactivity was quantified using ADP-induced light transmittance aggregometry (LTA) and the VerifyNow P2Y12 assay. Postdischarge TIMI major bleedings within 1 year after enrollment were recorded. In total, 25 major bleedings (3.0% of the study population) were observed. Patients with the CYP2C19*1/*17 and *17/*17 diplotypes exhibited a lower magnitude of platelet reactivity as compared with patients with the CYP2C19*1/*1 diplotype (for the light transmittance aggregometry-adjusted mean difference: -5.8%, 95% confidence interval: -9.6 to -2.1, P=0.002). Patients with the *1/*17 and *17/*17 genotype had a 2.7-fold increased risk in the occurrence of major bleedings [adjusted hazard ratio: 2.7, 95% confidence interval: 1.1-7.0, P=0.039]. The diplotypes *2/*17, *1/*2, and *2/*2 exhibited higher on-treatment platelet reactivity as compared with the wild type (P<0.0001). However, this was not translated into an altered risk on major bleedings as compared with the wild type [hazard ratio: 1.3 (0.45-4.0), P=0.60]. Results have not been adjusted for multiple testing. Patients with the CYP2C19*1/*17 and *17/*17 diplotype have a lower magnitude of on-treatment platelet reactivity and are at a 2.7-fold increased risk of postdischarge TIMI major bleeding events after coronary stenting than patients with the *1/*1 genotype. The diplotypes *2/*17, *1/*2, and *2/*2 are associated with increased on-treatment platelet reactivity; however, this is not translated into a lower risk of bleeding events.
    Pharmacogenetics and Genomics 03/2012; 22(3):169-75. · 3.61 Impact Factor
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    ABSTRACT: despite treatment with clopidogrel on top of aspirin, stent thrombosis (ST) still occurs being the most serious complication after percutaneous coronary interventions (PCIs). In this study, we aimed to determine the effect of variations in genes involved in the absorption (ABCB1 C1236T, G2677T/A, C3435T), metabolism (CYP2C19*2 and *3, CYP2C9*2 and *3, CYP3A4*1B and CYP3A5*3), and pharmacodynamics (P2Y1 A1622G) of clopidogrel on the occurrence of ST. the selected genetic variants were assessed in 176 subjects who developed ST while on dual antiplatelet therapy with aspirin and clopidogrel and in 420 control subjects who did not develop adverse cardiovascular events, including ST, within 1 year after stenting. The timing of the definite ST was acute in 66, subacute in 87, and late in 23 cases. The presence of the CYP2C19*2 and CYP2C9*3 variant alleles was significantly associated with ST (OR(adj): 1.7, 95% CI: 1.0-2.6, P = 0.018 and OR(adj): 2.4, 95% CI: 1.0-5.5, P = 0.043, respectively). The influence of CYP2C19*2 (OR(adj): 2.5, 95% CI: 1.1-5.5, P = 0.026) and CYP2C9*3 (OR(adj): 3.3, 95% CI: 1.1-9.9, P = 0.031) was most strongly associated with subacute ST. No significant associations of the other genetic variations and the occurrence of ST were found. carriage of the loss-of-function alleles CYP2C19*2 and CYP2C9*3 increases the risk on ST after PCI.
    European Heart Journal 12/2010; 31(24):3046-53. · 14.72 Impact Factor
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    ABSTRACT: The clinical efficacy of clopidogrel is hampered by a large interindividual variability in platelet inhibition. Polymorphisms in the P2RY12 receptor gene have been suggested to contribute to this variability, but previous studies included a relatively small number of patients and incompletely covered the common variation in the P2RY12 gene. The aim of this study was to comprehensively investigate the possible association between common variation in the entire P2RY12 locus and the magnitude of residual on-clopidogrel platelet reactivity measured by 2 commonly used platelet function assays in a large cohort of patients. A total of 1031 consecutive patients with coronary artery disease who were scheduled for elective percutaneous coronary interventions were enrolled. Platelet function was assessed by means of ADP-induced light-transmittance aggregometry and the VerifyNow P2Y12 assay. Six haplotype-tagging single nucleotide polymorphisms were carefully selected to comprehensively cover the total common variation in the P2RY12 gene and its flanking regulatory regions. Six common haplotypes were inferred from these haplotype-tagging single nucleotide polymorphisms (denoted A to F). Haplotype F was associated with significantly lower residual on-clopidogrel platelet reactivity compared with the reference haplotype A. The size of this effect per haplotype allele was approximately 5% aggregation in the ADP-induced light-transmittance aggregometry (P<0.05) and 11 P2Y12 reaction units in the VerifyNow P2Y12 assay (P<0.05). Common variation in the P2RY12 gene is a significant determinant of the interindividual variability in residual on-clopidogrel platelet reactivity in patients with coronary artery disease.
    Circulation Cardiovascular Genetics 10/2009; 2(5):515-21. · 6.73 Impact Factor
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    ABSTRACT: Community-acquired pneumonia (CAP) can be caused by a variety of microorganisms but is most frequently associated with Streptococcus pneumoniae and gram-negative bacteria like Haemophilus influenzae. Encapsulated bacteria are able to escape phagocytosis, unless they are bound by immunoglobulin G2 subclass antibodies. These antibodies interact with Fcgamma receptor IIa (Fcgamma-RIIa), thereby facilitating opsonophagocytosis of the encapsulated bacteria. We studied the relationship between the Fcgamma-RIIa-R/H131 polymorphism and the clinical course of CAP and pathogen-specific susceptibility. Regarding methodology, the Fcgamma-RIIa genotype R/H131 was determined in 200 patients with CAP and in 313 healthy controls and was correlated with the clinical course, laboratory parameters, and causative microorganism. The Fcgamma-RIIa-R/R131 genotype was found more frequently in patients with severe sepsis (odds ratio [OR], 2.55; 95% confidence interval [CI], 1.30 to 5.00; P < 0.01). The majority of patients in this group suffered from invasive pneumococcal disease. The duration of hospital stay was longer for patients with the Fcgamma-RIIa-R/R131 genotype. Fcgamma-RIIa genotypes were not associated with an increased risk of CAP in general; however, the Fcgamma-RIIa-R/R131 genotype was found more frequently in patients with CAP caused by H. influenzae than in controls (OR, 3.03; CI, 1.04 to 9.09; P < 0.05). In conclusion, the Fcgamma-RIIa-R/R131 genotype is associated with severity of CAP and is more frequent in CAP caused by H. influenzae.
    Clinical and vaccine Immunology: CVI 06/2009; 16(7):1087-90. · 2.60 Impact Factor