Study of APO E4, Coronary Risk Factors and Abdominal Aortic Diameter among Elderly Diabetic Patients

Abstract

Diabetes mellitus is an important public health problem worldwide because of its high prevalence and complications. Diabetes is associated with high mortality and morbidity as a result of coronary artery disease (CAD) and other atherosclerotic disease. Multiple factors contribute to the accelerated atherosclerosis in diabetes. These factors include excess prevalence of traditional risks such as obesity, hypertension, and dyslipidemia along with modifications of lipoproteins . APO E modulates lipoprotein transport and metabolism, and its polymorphism explains 4 to 15% of the variation in serum LDL-C at the population level. Several large cohort studies report that the APO E4 allele is associated with an increased risk of CAD and other studies found no association between the E4 allele and CAD. Among the vascular changes associated with diabetes, abdominal aorta in diabetic patients might be affected. And study found that APO E4 seems to be associated with atherosclerotic lesion area in the aorta. Information on the significance of APO E polymorphism in elderly subjects is limited and there are few studies of the effects of APO E on CVD in older people. The objectives of this study were to determine the APO E gene polymorphism in diabetic elderly in Egypt and to determine the association between APO E4 gene and coronary risk factors and its association with abdominal aortic diameter in diabetic elderly. This case control study enrolled ninety elderly who were recruited from the inpatients wards and outpatients clinics in Ain Shams University Hospital. They were subdivided into three groups: Group A: thirty elderly diabetic subjects with cardiovascular complications. Group B: thirty elderly diabetic subjects without cardiovascular complications. Group C: thirty elderly subjects without DM as the control group. Each patient underwent: comprehensive geriatric assessment, laboratory tests: FBS, 2hPP, lipid profile. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) to test the APO E gene polymorphism and abdominal ultrasound measurement of aortic diameter at the level of iliac bifurcation. This study revealed that APO E alleles in diabetic subjects with cardiovascular complications (Group A) were restricted to only two types E3 (60%) and E4 (40%). E4 tend to be more frequent(40.0%) in group A compared to the control group but the difference is not statistically significant (p=0.417) . while E2 allele was absent in Group A, on the other hand the frequency of APO E alleles in diabetic subjects without cardiovascular complications (Group B) was different there were three alleles with higher percentage of cases with E2 allele in Group B (53.3%) followed by E4 (36.7%) and only (10.0%) were E3 and in control group there was higher percentage of cases with E2 (46.7%) and (30.0%) for E4 and (23.3%) for E3. These results strongly suggest that the E2 allele has a protective role against cardiovascular complication in diabetic elderly. As regard APO E4 allele frequency there was no statistically significant difference between the three studied groups. Consequently there was no association between APO E4 and cardiovascular complications in elderly diabetic subjects.