T−786→C mutation in the 5′-flanking region of the endothelial nitric oxide synthase gene is associated with myocardial infarction, especially without coronary organic stenosis

Recently, we discovered a T−786→C mutation in the 5′-flanking region of the endothelial nitric oxide synthase gene that is associated with coronary spasm. The precise mechanism(s) of myocardial infarction (MI), especially without coronary organic stenosis, has not been elucidated, but it seems possible that coronary spasm plays a key role in the mechanism. In this study, we examined the frequency with which the T−786→C mutation occurred in 359 patients with MI who were compared with 195 controls. In the MI group, the frequency of C/C, C/T, and T/T genotypes was 1%, 22%, and 77%, respectively. In the control group, the frequency of C/C, C/T, and T/T genotypes were 0%, 8%, and 92%, respectively. The frequency of the C allele was significantly higher in the MI group than in the control group (p <0.001). In the MI group, 30 of 359 patients (8%) with MI had no stenosed vessels angiographically, 158 (44%) had 1 stenosed vessel, 80 (22%) had 2 stenosed vessels, and 91 (25%) exhibited 3 stenosed vessels. Total and low-density lipoprotein cholesterol levels and the incidence of diabetes mellitus increased as the number of stenosed vessels increased (p <0.01, respectively). The frequency of the T−786→C mutation was significantly higher in MI patients with no stenosed vessels (50%) than in those with stenosed vessels (p <0.003). In conclusion, the T−786→C mutation was strongly associated with MI, especially without coronary arterial stenosis, in Japanese patients. The association may be due to the impaired effects of nitric oxide in the cardiovascular system.