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Objective: Human paraoxonase 1 (PON1) is an HDL-associated enzyme with anti-oxidant/anti-inflammatory properties that has been suggested to play an important protective role against coronary artery disease (CAD). The PON1 promoter -108C/T polymorphism has been analyzed in numerous association studies as a genetic marker for CAD, however, with controversial results. The aim of this study was to evaluate the association of PON-1 promoter -108C/T polymorphism with the risk of myocardial infarction (MI) in the Tunisian male population.Methods: A total of 815 subjects were recruited, including 318 healthy controls and 497 MI patients. Genotypes were determined by PCR-RFLP method. Genotype/allele frequencies were compared in patients and controls using the chi-square test.Results: Genotype distributions and allele frequencies of PON-1 promoter -108C/T polymorphism were different among the control and MI groups. Patients with MI had significantly higher frequency of the TT genotype compared to controls [29.2% vs. 25.5%; OR (95% CI), 1.67 (1.52-2.49); p=0.010]. The MI patient group showed a significant higher frequency of the T allele compared to the controls [0.56 vs. 0.51; χConclusion: The present study showed a significant and independent association between the PON-1 promoter -108C/T polymorphism and MI in the Tunisian male population.

Background: Elevated plasma total homocysteine (tHcy), a risk factor for coronary artery disease (CAD), is due to defects in genes encoding for enzymes involved in tHcy metabolism or from inadequate status of vitamins involved in tHcy disposal. Methionine synthase (MS), a vitamin B 12 -dependent enzyme, catalyses the remethylation of homocysteine to methionine using a methyl group donated by 5-methyltetrahydrofolate, which is the major circulating form of folate in the body. Functional genetic variants of the MS may alter tHcy as well as folate levels which are independent risk factors for CAD. The influence of a common genetic polymorphism 2756A> G of the MS gene (MTR) on plasma tHcy, folate and vitamin B 12 levels and its relation to the risk of myocardial infarction (Ml) in a Tunisian case-control study was investigated. Methods: A total of 321 Tunisian patients with Ml and 343 healthy controls were included in the study. The 2756A> G variant of the MTR was determined by polymerase chain reaction-restriction fragment length polymorphism analysis. Plasma tHcy was assessed with a fluorescent polarising immunoassay method. Plasma vitamin B 12 and folate were determined by microparticular enzyme immunoassay and ion-capture, respectively. Results: A significant difference in genotype distribution and allele frequency was observed between patients and controls. Patients with Ml had a frequency of 1.9% for the GG genotype, 26.2% for the AG genotype and 72% for the AA genotype. Controls had a frequency of only 0.9% for the GG genotype, 18.7% for the AG genotype and 80.5% for the AA genotype (X 2 =6.97, p=0.03). The Ml patient group showed a significant higher frequency of the G allele compared to controls (0.149 vs. 0.101; OR 1.55; 95% Cl 1.10-2.18; p=0.008). The association between the 2756A>G variant in the gene encoding MS and Ml was no longer significant after adjustment for other well-established risk factors. When clinical and laboratory values were compared amongst genotypes in the study groups, no significant differences were noted. Conclusions: The present study showed a significant but not independent association between the 2756A> G polymorphism of the MTR (presence of G allele) and Ml in the Tunisian population.

Background: Nitric oxide (NO) produced by endothelial nitric oxide synthase (eNOS) mediates endothelium-dependent vasodilatation and antithrombotic action. Controversial results regarding the association of eNOS gene (NOS3) polymorphisms with myocardial infarction (Ml) have been reported. In the present study, we examined a possible association between a 27-base pair (bp) repeat polymorphism in intron 4 of the NOS3 gene and Ml in a subgroup of the Tunisian population. Methods: A total of 310 Tunisian patients with Ml and 250 healthy controls were included in the study. The NOS3 gene intron 4a4b variable number of tandem repeats polymorphism was analyzed by PCR. Results: A significant difference in genotype distribution and allele frequency was observed between patients and controls. Patients with Ml had a frequency of 4.8% for the 4a4a genotype, 33.9% for the 4a4b genotype and 61.3% for the 4b4b genotype. Controls had a frequency of only 1.6% for the 4a4a genotype, 24.4% for the 4a4b genotype and 74.0% for the 4b4b genotype (Χ 2 = 11.81, p=0.003). The Ml patient group showed a significant higher frequency of the 4a allele compared to controls (0.218 vs. 0.139; X 2 =5.81, p=0.01). Conclusions: In the present study, a significant association between the NOS34a/4b gene polymorphism (presence of 4a allele) and Ml in the Tunisian population was found.