Evidence for association of a common variant of the endothelial nitric oxide synthase gene ([Glu.sup.298][right arrow]Asp polymorphism) to the presence, extent, and severity of coronary artery disease. (Cardiovascular Medicine).

Background: Genetic variants of endothelial nitric oxide synthase (eNOS) could influence individual susceptibility to coronary artery disease.

Objective: To assess whether [Glu.sup.298][right arrow]Asp polymorphism of the eNOS gene is associated with the occurrence and severity of angiographically defined coronary artery disease in the Italian population.

Methods: Palymerase chain reaction/restriction fragment length polymorphism analysis was done to detect the [Glu.sup.298][right arrow]Asp variant of the eNOS gene in 201 patients with coronary artery disease and 114 controls. The severity of coronary artery disease was expressed by the number of affected vessels and by the Duke scoring system.

Results: The frequencies of the eNOS Glu/Glu, Glu/Asp, and Asp/Asp genotypes in the coronary artery disease group were significantly different from those of controls (45.3%, 38.8%, and 15.9% v 42.1%, 51.8%, and 6.1%, respectively; [chi square] = 8.589, p = 0.0136). In comparison with subjects who had a [Glu.sup.298] allele in the eNOS gene, the risk of coronary artery disease was increased among Asp/Asp carriers (odds ratio 2.9, 95% confidence interval 1 .2 to 6.8, p = 0.01) and was independent of the other common risk factors (p = 0.04). There was a significant association between the eNOS [Glu.sup.298][right arrow]Asp variant and both the number of stenosed vessels (mean (SEM), 2.3 (0.1) for Asp/Asp v 1.9 (0.1) and 1.8 (0.1) for Glu/Glu and Glu/Asp, respectively; p = 0.01) and the Duke score (56.1(3.1) for Asp/Asp v 46.7 (2.0) and 46.1 (1.9) for Glu/Glu and Glu/Asp, respectively; p 0.02).

Conclusions: [Glu.sup.298][right arrow]Asp polymorphism of the eNOS gene appears to be associated with the presence, extent, and severity of angiographically assessed coronary artery disease.

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Epidemiological studies indicate that hyperlipidaemia, hypertension, cigarette smoking, diabetes, and obesity are risk factors for coronary artery disease. (1-3) Control of these environmental risk factors has, however, been ineffective in completely predicting development of the atherosclerotic process, suggesting that specific genetic predisposition should be taken into account as well. (4 5)

Vascular endothelium modulates blood vessel wall homeostasis through the production of factors regulating vessel tone, coagulation state, cell growth, cell death, and leucocyte trafficking. (6) One of the most important endothelial cell products is nitric oxide (NO), which is synthesised from L-arginine by the enzyme endothelial nitric oxide synthase (eNOS). (7) NO plays a key role in the relaxation of vascular smooth muscle, inhibits platelet and leucocyte adhesion to the endothelium, reduces vascular smooth muscle cell migration and proliferation, and limits the oxidation of atherogenic low density lipoproteins. (8) Moreover, it has been shown that eNOS inhibition accelerates atherosclerosis in animal models, and that abnormalities of the endothelial NO pathway are present in humans with atherosclerosis. (9 10) This evidence suggests that NO may inhibit several key steps in the atherosclerotic process and that an alteration of NO production within the vascular endothelium could contribute to the pathogenes is of atherosclerosis. Thus eNOS could be a candidate gene for atherosclerosis.

Several polymorphisms have been identified in the eNOS gene, among which is one located in exon 7 (G984T) which modifies its coding sequence ([Glu.sup.298][right arrow]Asp) Associations between this variant and coronary spasm, coronary artery disease, and acute myocardial infarction have been reported, but data on its relation with disease severity are lacking. (11 12) In this paper, we describe the associations between the [Glu.sup.298][right arrow]Asp polymorphism of the eNOS gene and the occurrence and severity of angiographically defined coronary artery disease in the Italian population.

METHODS

Study population

We studied 201 patients consecutively admitted to our institution with angiographically proven coronary artery disease (more than 50% stenosis affecting at least one vessel) and 114 control subjects …