Jean-Luc Reny

Adenosine Diphosphate–Induced Platelet Aggregation Is Associated With P2Y12 Gene Sequence Variations in Healthy Subjects

Background—The adenosine diphosphate (ADP) receptor P2Y12 plays a pivotal role in platelet aggregation, as demonstrated by the benefit conferred by its blockade in patients with cardiovascular disease. Some studies have shown interindividual differences in ADP-induced platelet aggregation responses ex vivo, but the mechanisms underlying this variability are unknown. Methods and Results—We examined ADP-induced platelet aggregation responses in 98 healthy volunteers, and we identified 2 phenotypic groups of subjects with high and low responsiveness to 2 &mgr;mol/L ADP. This prompted us to screen the recently identified Gi-coupled ADP receptor gene P2Y12 for sequence variations. Among the 5 frequent polymorphisms thus identified, 4 were in total linkage disequilibrium, determining haplotypes H1 and H2, with respective allelic frequencies of 0.86 and 0.14. The number of H2 alleles was associated with the maximal aggregation response to ADP in the overall study population (P =0.007). Downregulation of the platelet cAMP concentration by ADP was more marked in 10 selected H2 carriers than in 10 noncarriers. Conclusions—In healthy subjects, ADP-induced platelet aggregation is associated with a haplotype of the P2Y12 receptor gene. Given the crucial role of the P2Y12 receptor in platelet functions, carriers of the H2 haplotype may have an increased risk of atherothrombosis and/or a lesser clinical response to drugs inhibiting platelet function.

P2Y12 H2 Haplotype Is Associated With Peripheral Arterial Disease A Case-Control Study

Background—We recently described a gain-of-function haplotype, called H2, of the adenosine diphosphate (ADP) receptor P2Y12 gene associated with increased ADP-induced platelet aggregation ex vivo in healthy volunteers. Because platelets play a key role in atherosclerosis and arterial thrombosis, we tested the possible link between the H2 haplotype and the risk of peripheral arterial disease (PAD) in a case-control study. Methods and Results—We studied 184 consecutive male patients under 70 years of age with PAD and 330 age-matched control subjects free of symptomatic PAD and with no cardiovascular history. Mean age was 57.1±7.2 years (cases) and 56.7±7.6 years (control subjects). The H2 haplotype was more frequent in patients with PAD than in control subjects (30% and 21%, respectively; OR, 1.6; CI, 1.1 to 2.5; P =0.02 in univariate analysis). This association with PAD remained significant in multivariate regression analysis (OR, 2.3; CI, 1.4 to 3.9; P =0.002) after adjustment for diabetes, smoking, hypertension, hypercholesterolemia, and other selected platelet receptor gene polymorphisms. Conclusions—These data point to a role of the H2 haplotype in atherosclerosis and raise the possibility of relative thienopyridine resistance in carriers of the P2Y12 H2 haplotype.

P2y: A Case-control Study H2 Haplotype Is Associated With Peripheral Arterial Disease: A Case-control Study

Background—We recently described a gain-of-function haplotype, called H2, of the adenosine diphosphate (ADP) receptor P2Y12 gene associated with increased ADP-induced platelet aggregation ex vivo in healthy volunteers. Because platelets play a key role in atherosclerosis and arterial thrombosis, we tested the possible link between the H2 haplotype and the risk of peripheral arterial disease (PAD) in a case-control study. Methods and Results—We studied 184 consecutive male patients under 70 years of age with PAD and 330 age-matched control subjects free of symptomatic PAD and with no cardiovascular history. Mean age was 57.1±7.2 years (cases) and 56.7±7.6 years (control subjects). The H2 haplotype was more frequent in patients with PAD than in control subjects (30% and 21%, respectively; OR, 1.6; CI, 1.1 to 2.5; P =0.02 in univariate analysis). This association with PAD remained significant in multivariate regression analysis (OR, 2.3; CI, 1.4 to 3.9; P =0.002) after adjustment for diabetes, smoking, hypertension, hypercholesterolemia, and other selected platelet receptor gene polymorphisms. Conclusions—These data point to a role of the H2 haplotype in atherosclerosis and raise the possibility of relative thienopyridine resistance in carriers of the P2Y12 H2 haplotype.

The factor II G20210A gene polymorphism, but not factor V Arg506Gln, is associated with peripheral arterial disease: results of a case–control study

Summary.  Background: The FIIG20210A polymorphism has been associated with arterial wall thickness and atherothrombotic diseases in selected subgroups. The FVArg506Gln polymorphism does not seem to be associated with arterial diseases. Few data are available on these polymorphisms and the risk of peripheral arterial disease (PAD). Objectives: To study the association between the FIIG20210A and FVArg506Gln polymorphisms and PAD and its clinical severity. To examine the potential interactions with traditional vascular risk factors. Patients and methods: We studied 184 consecutive male patients under 70 years of age with symptomatic PAD and 330 age‐matched male controls free of symptomatic PAD and with no cardiovascular history. We evaluated the FIIG20210A and FVArg506Gln polymorphisms in all subjects. Results: Mean age was 57.1 ± 7.2 years (cases) and 56.7 ± 7.6 years (controls). The FII20210A allele was more frequent in PAD patients with odds ratios (OR) of 3.77 (1.39–10.2) in univariate analysis and 4.30 (1.3–14.7) after adjustment for diabetes, smoking, hypertension and hypercholesterolemia. In smokers or past smokers the magnitude of the association was markedly increased but there was no evidence of an interaction between tobacco exposure and FIIG20210A. In case subjects, the FII20210A allele was also associated with critical ischemia [OR = 4.1 (1.1–15.7), P = 0.039 in multivariate analysis]. FVArg506Gln was not associated with PAD [OR = 0.65 (0.27–1.54) and 0.77 (0.28–2.1) in univariate and multivariate analyses, respectively]. Conclusions: The FIIG20210A gene polymorphism may be a risk factor for PAD and its severity. In contrast, the FVArg506Gln polymorphism is not associated with PAD.

P2Y1 gene polymorphism and ADP-induced platelet response.

1 Mannucci PM, Duga S, Peyvandi F. Recessively inherited coagulation disorders. Blood 2004; 104: 1243–52. 2 Maghzal GJ, Brennan SO, Homer VM, George PM. The molecular mechanisms of congenital hypofibrinogenaemia. Cell Mol Life Sci 2004; 61: 1427–38. 3 Neerman-Arbez M. The molecular basis of inherited afibrinogenaemia. Thromb Haemost 2001; 86: 154–63. 4 Hanss MM, Ffrench PO, Mornex JF, Chabuet M, Biot F, De Mazancourt P, Dechavanne M. Two novel fibrinogen variants found in patients with pulmonary embolism and their families. J Thromb Haemost 2003; 1: 1251–7. 5 Homer VM, Brennan SO, Ockelford P, George PM. Novel fibrinogen truncation with deletion of Bbeta chain residues 440–461 causes hypofibrinogenaemia. Thromb Haemost 2002; 88: 427–31. 6 Zhang JZ, Redman CM. Identification of Bbeta chain domains involved in human fibrinogen assembly. J Biol Chem 1992; 267: 21727– 32. 7 Brennan SO, Maghzal G, Shneider BL, Gordon R, Magid MS, George PM. Novel fibrinogen gamma 375 Arg fi Trp mutation (fibrinogen Aguadilla) causes hepatic endoplasmic reticulum storage and hypofibrinogenemia. Hepatology 2002; 36: 652–8. 8 Huang S, Mulvihill ER, Farrell DH, Chung DW, Davie EW. Biosynthesis of human fibrinogen. Subunit interactions and potential intermediates in the assembly. J Biol Chem 1993; 268: 8919–26. 9 Okumura N, Terasawa F, Yonekawa O, Hamada E, Kaneko H. Hypofibrinogenemia associated with a heterozygous C>T nucleotide substitution at position )1138 bp of the 5¢flanking region of the fibrinogen Aa-chain gene. Ann NY Acad Sci 2001; 936: 526–30. 10 Brennan SO, Hammonds B, George PM. Aberrant hepatic processing causes removal of activation peptide and primary polymerisation site from fibrinogen Canterbury (A alpha 20 Val fi Asp). J Clin Invest 1995; 96: 2854–8. 11 Farrell DH, Huang S, Davie EW. Processing of the carboxyl 15-aminoacid extension in the alpha-chain of fibrinogen. J Biol Chem 1993; 268: 10351–5.

LETTER TO THE EDITOR: P2Y1 gene polymorphism and ADP-induced platelet response

1 Mannucci PM, Duga S, Peyvandi F. Recessively inherited coagulation disorders. Blood 2004; 104: 1243–52. 2 Maghzal GJ, Brennan SO, Homer VM, George PM. The molecular mechanisms of congenital hypofibrinogenaemia. Cell Mol Life Sci 2004; 61: 1427–38. 3 Neerman-Arbez M. The molecular basis of inherited afibrinogenaemia. Thromb Haemost 2001; 86: 154–63. 4 Hanss MM, Ffrench PO, Mornex JF, Chabuet M, Biot F, De Mazancourt P, Dechavanne M. Two novel fibrinogen variants found in patients with pulmonary embolism and their families. J Thromb Haemost 2003; 1: 1251–7. 5 Homer VM, Brennan SO, Ockelford P, George PM. Novel fibrinogen truncation with deletion of Bbeta chain residues 440–461 causes hypofibrinogenaemia. Thromb Haemost 2002; 88: 427–31. 6 Zhang JZ, Redman CM. Identification of Bbeta chain domains involved in human fibrinogen assembly. J Biol Chem 1992; 267: 21727– 32. 7 Brennan SO, Maghzal G, Shneider BL, Gordon R, Magid MS, George PM. Novel fibrinogen gamma 375 Arg fi Trp mutation (fibrinogen Aguadilla) causes hepatic endoplasmic reticulum storage and hypofibrinogenemia. Hepatology 2002; 36: 652–8. 8 Huang S, Mulvihill ER, Farrell DH, Chung DW, Davie EW. Biosynthesis of human fibrinogen. Subunit interactions and potential intermediates in the assembly. J Biol Chem 1993; 268: 8919–26. 9 Okumura N, Terasawa F, Yonekawa O, Hamada E, Kaneko H. Hypofibrinogenemia associated with a heterozygous C>T nucleotide substitution at position )1138 bp of the 5¢flanking region of the fibrinogen Aa-chain gene. Ann NY Acad Sci 2001; 936: 526–30. 10 Brennan SO, Hammonds B, George PM. Aberrant hepatic processing causes removal of activation peptide and primary polymerisation site from fibrinogen Canterbury (A alpha 20 Val fi Asp). J Clin Invest 1995; 96: 2854–8. 11 Farrell DH, Huang S, Davie EW. Processing of the carboxyl 15-aminoacid extension in the alpha-chain of fibrinogen. J Biol Chem 1993; 268: 10351–5.

P2Y1 gene polymorphism and ADP-induced platelet response: Letter to the Editor

1 Mannucci PM, Duga S, Peyvandi F. Recessively inherited coagulation disorders. Blood 2004; 104: 1243–52. 2 Maghzal GJ, Brennan SO, Homer VM, George PM. The molecular mechanisms of congenital hypofibrinogenaemia. Cell Mol Life Sci 2004; 61: 1427–38. 3 Neerman-Arbez M. The molecular basis of inherited afibrinogenaemia. Thromb Haemost 2001; 86: 154–63. 4 Hanss MM, Ffrench PO, Mornex JF, Chabuet M, Biot F, De Mazancourt P, Dechavanne M. Two novel fibrinogen variants found in patients with pulmonary embolism and their families. J Thromb Haemost 2003; 1: 1251–7. 5 Homer VM, Brennan SO, Ockelford P, George PM. Novel fibrinogen truncation with deletion of Bbeta chain residues 440–461 causes hypofibrinogenaemia. Thromb Haemost 2002; 88: 427–31. 6 Zhang JZ, Redman CM. Identification of Bbeta chain domains involved in human fibrinogen assembly. J Biol Chem 1992; 267: 21727– 32. 7 Brennan SO, Maghzal G, Shneider BL, Gordon R, Magid MS, George PM. Novel fibrinogen gamma 375 Arg fi Trp mutation (fibrinogen Aguadilla) causes hepatic endoplasmic reticulum storage and hypofibrinogenemia. Hepatology 2002; 36: 652–8. 8 Huang S, Mulvihill ER, Farrell DH, Chung DW, Davie EW. Biosynthesis of human fibrinogen. Subunit interactions and potential intermediates in the assembly. J Biol Chem 1993; 268: 8919–26. 9 Okumura N, Terasawa F, Yonekawa O, Hamada E, Kaneko H. Hypofibrinogenemia associated with a heterozygous C>T nucleotide substitution at position )1138 bp of the 5¢flanking region of the fibrinogen Aa-chain gene. Ann NY Acad Sci 2001; 936: 526–30. 10 Brennan SO, Hammonds B, George PM. Aberrant hepatic processing causes removal of activation peptide and primary polymerisation site from fibrinogen Canterbury (A alpha 20 Val fi Asp). J Clin Invest 1995; 96: 2854–8. 11 Farrell DH, Huang S, Davie EW. Processing of the carboxyl 15-aminoacid extension in the alpha-chain of fibrinogen. J Biol Chem 1993; 268: 10351–5.

Vascular risk levels affect predictive value of platelet reactivity for the occurrence of MACE in clopidogrel treatment

Prior studies have shown an association between high on-clopidogrel platelet reactivity (PR) and the risk of major adverse cardiovascular events (MACE). However, large intervention trials on PR-tailored treatments have been neutral. The role and usefulness of PR with regard to levels of cardiovascular risk are unclear. We undertook a systematic review and meta-analysis of individual patient data on MACE outcomes (acute coronary syndromes (ACS), ischaemic strokes, and vascular deaths) in relation to PR and its interaction with cardiovascular risk levels. PR was determined using ADP-induced light transmission aggregometry with a primary concentration of 20 µM ADP. Thirteen prospective studies totaled 6,478 clopidogrel-treated patients who experienced 421 MACE (6.5 %) during a median follow-up of 12 months. The strength of the association between the risk of MACE and PR increased significantly (p=0.04) with the number of risk factors present (age> 75 years, ACS at inclusion, diabetes, and hypertension). No association was detected in patients with no risk factor (p=0.48). In patients presenting one risk factor, only high-PR was associated with an increased risk of MACE (HR 3.2, p=0.001). In patients presenting ≥ 2 risk factors, the increase of risk started from medium-PR (medium-PR: HR=2.9, p=0.0004; high-PR: HR=3.7, p=0.0003). PR allowed the reclassification of 44 % of the total population to a different risk level for the outcome of MACE, mostly in intermediate or high risk patients. In conclusion, the magnitude of the association between PR and MACE risk is strongly dependent on the level of cardiovascular risk faced by patients on clopidogrel.

Utilisation des antiplaquettaires : indications et limites chez les patients âgés

Les agents antiplaquettaires recents, tels que le ticagrelor et le prasugrel, ont apporte un benefice en termes de reduction des evenements ischemiques dans le cadre des syndromes coronariens aigus (SCA) et de prevention secondaire durant les mois suivants. Ces medicaments, tout comme le clopidogrel, augmentent le risque hemorragique lorsqu’ils sont combines a l’aspirine et leur utilisation chez les patients âges ou tres âges n’est pas simple. Les patients âges de plus de 75 ans souffrant d’un SCA doivent beneficier, comme les plus jeunes, d’une combinaison d’aspirine et de ticagrelor ou de clopidogrel avec les doses de charge requises. Il est recommande d’eviter le prasugrel pour cette population âgee. Les patients ayant une fibrillation atriale et une maladie coronarienne en dehors d’un evenement ischemique aigu ne devraient beneficier que d’une anticoagulation seule, sans adjonction d’antiplaquettaires en dehors de cas particulier a haut risque de thrombose coronaire. L’existence d’antecedents hemorragiques severes chez des patients âges doit faire reconsiderer les durees de prescription des associations d’antiplaquettaires et parfois meme le principe de ces associations en prenant en compte leur rapport benefice-risque dans le contexte individuel. Les endoprotheses vasculaires de derniere generation vont certainement contribuer a la modulation du regime antiplaquettaire, en particulier chez ces patients a haut risque hemorragique comme la population âgee.