Jean-Noël Fiessinger

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.

Interdonor variability of platelet response to thrombin receptor activation : influence of PlA2 polymorphism

Considering that platelet response to thrombin receptor activation might be critical for the development of arterial thrombosis, we measured the dense granule release under stimulation by the thrombin receptor activating peptide (TRAP) in a series of 102 healthy volunteers. The threshold TRAP concentration which initiated a secretion ranged from 3 to 20u2003μm. A good concordance (79%, ku2003=u20030.677) between two tests performed at a 1 month interval indicated that platelet response to thrombin receptor activation was characteristic of each individual donor. Since the threshold concentration required to initiate secretion corresponded to the threshold concentration which induced a biphasic aggregation, all volunteers were genotyped for the PlA2 polymorphism, the Pro33 variant of GPIIIa. Platelets from subjects with the PlA2 polymorphism required higher TRAP concentrations to aggregate than those from subjects with no PlA2 allele (Pu2003=u20030.0012). However, they also required a higher ADP concentration to aggregate. In order to exclude any influence of GPIIIa polymorphism on TRAP‐induced secretion, we studied the variability of platelet response to TRAP among the 77 individuals with no PlA2 allele, and found the same interdonor variability with the same distribution of threshold TRAP concentrations as for the 102 individuals. The results suggest that (i) platelet secretion in response to thrombin receptor activation could be a genetically controlled phenotype independent of the GPIIIa polymorphism; (ii) the PlA2 polymorphism is associated with platelet hypoaggregability.

Thromboangiitis obliterans and endothelial function

Eur J Clin Invest 2010; 40 (6): 518–526

Influence of three potential genetic risk factors for thrombosis in 43 families carrying the factor V Arg 506 to Gln mutation

The factor V (FV) Arg 506 to Gln mutation is the most common abnormality observed in familial thrombophilia. Many studies have shown that its clinical expression differs among families and among carriers. Some thrombotic patients carry an additional genetic risk factor such as protein C, protein S or antithrombin deficiency. We sought to identify other genetic risk factors potentially favouring expression of the thrombotic phenotype in 370 members of 43 families with the FV Arg 506 to Gln mutation. We analysed three candidate polymorphisms in genes involved in the PC anticoagulant pathway, consisting of two polymorphic sites in the 5′ non‐transcribed region of the PC gene, −1654 C/T and −1641 A/G, with three known combinations (TA, CA and CG) that influence the protein C plasma level; one polymorphic site (4070 A/G) in exon 13 of the FV gene, which influences the plasma factor V concentration, and one polymorphic site (677 C/T) in the methylenetetrahydrofolate reductase gene, which is often associated with moderate hyperhomocysteinaemia. The distribution of these different polymorphisms was similar in patients with a history of thrombosis and those who remained asymptomatic, ruling out the possibility that each of these polymorphisms alone can play a role in the onset of thrombosis in carriers of the FV Arg 506 to Gln mutation.

Molecular basis for hereditary antithrombin III quantitative deficiencies : a stop codon in exon IIIa and a frameshift in exon VI

Summary. Antithrombin III (AT III) is an inhibitor of serine protease (serpin) comprising 432 amino acids. Quantitative AT III deficiencies are associated with a high risk of thrombotic disease. Although this risk is smaller in patients with qualitative AT III deficiencies, the molecular defects characterizing the latter have been the subject of many studies. However, in quantitative AT III deficiencies, only three mutations have been described: Pro 407 to Leu and Ala 404 to Thr (both located in the C‐terminal part of the AT III molecule) and also a frameshift in exon IIIa.

Microangiopathie du pseudoxanthome élastique: Aspects capillaroscopiques

OBJECTIVEnThe aim of this study was to describe, for the first time, the capillary angio-architecture during pseudoxanthoma elasticum, a rare genetic disease related to mutations in the ABCC6 gene, of which the systemic calcifying involvement is responsible notably for very severe cardiovascular complications. Method Seven patients suffering from clinically and histologically documented confirmed pseudoxanthoma elasticum were examined with capillaroscopy, the absence of concomitant connective tIssue disease or diabetes having been checked beforehand.nnnRESULTSnAll the patients exhibited a microangiopathy, characterised by normal capillary density, frequent pericapillary oedema, excessively coiled fibres with a significantly increased number of minor dystrophies and, to varying degrees, a slowing down of capillary blood flow demonstrated by a sludge phenomenon.nnnCONCLUSIONnThis descriptive study shows that a microangiopathy exists during pseudoxanthoma elasticum. However, the latter is not specific and a double blind controlled study is required to confirm these results. The discovery of genotype/phenotype correlations in this disease would provide a place for capillaroscopy in the diagnostic strategy in young patients or in the assessment of the cardiovascular involvement.