[Apolipoprotein E and angiotensin-converting enzyme gene polymorphisms as risk factors of coronary disease]. / Implication du polymorphisme génétique de l'apolipoprotéine E et de l'enzyme de converstion de l'angiotensine dans l'athérosclérose coronarienne.

The objective of this study was to test the hypothesis that apo E (RFLP, HhaI) and/or angiotensin-converting enzyme (ACE) (ins16del) are associated with higher risk for coronary heart disease. We investigated 250 patients who underwent complete cardiac examination comprising coronary angioplasty and biological analysis (CT, HDLc, LDLc, TG, apo A and apo B). Prevalence of the alleles of apo E and ACE was assessed by molecular analysis. Patients without stenosis or with non-significant stenosis (> 50% of the vascular lumen) were used as reference group (141 patients). Those presenting a significant stenosis of the coronary artery (. 50% of the vascular lumen) were considered as cases (109 patients). The relative frequency of the e 4 allele was significantly higher in cases than in reference group (p > 0.02). A strong association have been found between coronary heart disease and apo E polymorphism (2 = 8.91; p > 0.05). The presence of the e 4 allele increase the risk of atherosclerosis (RR = 2.71; IC95%: 1.25-5.90; p > 0.02) compared to e 3 allele. Also, subjects with D allele were more frequent in cases than in reference group (p > 0.001). A significant association was noted between ACE polymorphism and coronary heart disease (2 = 42.15; p > 0.001). This relationship was positive (rho de Spearman = 0.39; p > 0.01). With D/D homozygotes patients, the RR for coronary heart disease was 19.10 (p > 0.001), while The RR with I/D heterozygotes was 6.91 (p > 0.001) compared to I/I homozygotes. A significant interaction have been shown up between D/D genotype and arterial hypertension (HTA) (2 de Wald = 16.10; p > 0.001). The multivariate analysis showed that the chronic smoking, diabetes, hypoapolipoproteinemia A, interactive effects between D/D and HTA, I/D and obesity, and between D/D and hypertriglyceridemia were the major significant factors to take into consideration in our population. We also note that subjects with both D and e 4 alleles were presenting a high risk to coronary heart disease (RR = 5.93; IC95%: 2.00-17.55; p > 0.01). Thus, those two alleles (4 and D) appears to be important cardiovascular risk factors in the moroccan population.

[Homocysteine, lipoprotein (a): risk factors for coronary heart disease]. / Homocystéine, lipoprotéine (a): acteurs de risque de l'athérosclérose coronarienne.

Our data suggest that the hyperhomocysteinemia and/or increased plasma level of lipoprotein Lp(a) are risk factors for coronary heart disease. We investigated 178 patients who underwent complete cardiac examination comprising coronary angiography and biological analysis (CT, HDL-c, LDL-c, TG, and apoAI, apoB, homocysteine and Lp(a)). Patients presenting a significant stenosis of the coronary artery ( 50% of the vascular lumen) were considered as cases (113 patients). Those without stenosis or with non-significant stenosis (< 50% of the vascular lumen) were used as controls (65 subjects). Homocysteinemia was significantly higher in cases than in control subjects (8.26 mol/L (2.34 versus 17.85 (2.34, p < 0.001). A strong association between coronary heart disease and homocystein has been found (Eta(2) = 0.76). The OR were 0.16 when homocystein level was lower than 15 mol/L, and 27.78 when homocysteine level was upper than or equal to 15 mol/L. The RR was 5.16 (95% IC = 3.66-6.66, p < 0.001). Even though there was a significant correlation between tabagic impregnation and homocysteinemia (Spermann's rho = 0.37, p < 0.05), there was no interactive effect between these two factors and coronary disease (Wald khi2 = 0.086, p > 0.05). Therefore, no association was found between homocyteinemia and other coronary heart disease risk factors. The Lp(a) levels were significantly higher in cases than in controls subjects (188 (84 mg/L in control subjects versus 590 (199 in cases, p < 0.001). A stronger relationship was noted between coronary heart disease and Lp(a) (Eta (2) = 0.66). The OR were 0.09 when lipoprotein (a) levels were lower than 350 mg/L, and 5,88 when Lp(a) levels were higher than or equal to 350 mg/L. The estimate RR was 6.47 (95% IC = 4.39-8.55, p < 0.001). The level of Lp(a) was positively correlated with the severity of coronary heart disease (Spermann's rho = 0.95, p < 0.001). A weak correlation between Lp(a) and LDL-c was observed (Spermann's rho = 0.12, p = 0.048). But the multivariate analysis didn't show interactive effect between these two factors and coronary disease (khi2 de Wald = 0.264, p > 0.05). No association was noted between Lp(a) and the others risk factors. Moreover, a positive correlation between the levels of homocysteine and those of Lp(a) was found (Spermann's rho = 0.54, p < 0.001). In contrast their effect on coronary heart disease seems to be independant (Wald khi2 = 2.957, p > 0.05). Thus, these two parameters appear as independant risk factors for coronary heart disease.