Impact of Apo E Genetic Polymorphism on Coronary Risk Factors and Carotid intimal-medial Thickness in Diabetic Elderly

Abstract

Type 2 diabetes mellitus is a disease with high incidence and prevalence in Egypt. It is associated with high incidence of cardiovascular disease and complications. It has been suggested that the ApoE gene polymorphism may be associated with predisposition to diabetic complications (both micro and macrovascular complications). Individuals with different ApoE genotypes have different susceptibilities to CAD. Studies have shown that the E4 allelic variant is associated with the mechanisms of development of atherosclerosis. Several large cohort studies report that the ApoE4 allele is associated with an increased risk of CAD and other studies found no association between the E4 allele and CAD. Information on the significance of ApoE polymorphism in elderly subjects is limited and there are few studies of the effects of ApoE on CVD in older people. Carotid atherosclerosis was considered a surrogate marker for coronary atherosclerosis, and thus, the measurement of CIMT by ultrasound provides a quantitative basis for the extent of atherosclerosis.  Summary 123 Our study aimed to characterize the genotypes of ApoE in diabetic elderly patients from Egypt in order to describe the allelic frequency of the ApoE gene and its relation to coronary risk factors and carotid intimal- medial thickness. The study enrolled ninety elderly subjects who were divided into thirty elderly diabetic subjects with cardiovascular complications (group A), thirty elderly diabetic subjects without cardiovascular complications (group B) and thirty elderly subjects without DM as the control group (group C). The three groups were matched for age and sex Every study participant was subjected to the following: 1. Ethical considerations. 2. Comprehensive geriatric assessment. 3. Determination of fasting blood sugar level and 2 hour postprandial blood sugar. 4. Determination of serum lipids (total cholesterol, LDL, HDL and triglycerides). 5. Apo E genotyping was tested by Polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP). 6. Measurement of carotid intima-media thickness by carotid duplex.  Summary 124 The current study revealed that in diabetic subjects with cardiovascular complications (Group A), the most frequent allele was E3 (60%) followed by E4 (40%) E2 allele was not presented, while in diabetic subjects without cardiovascular complications (Group B) the most frequent allele was E2 (53.3%) followed by E4 (36.7%) and only (10.0%) were E3 and in control group the most frequent allele was E2 (46.7%) followed by E4 (30.0%) and (23.3%) for E3. Our study of ApoE genetic polymorphism evidenced that E2 allele carriers were significantly more frequent in either control or diabetics without cardiovascular complications while, there was no statistically significant difference between the 3 groups as regard the frequency of ApoE4 allele, Consequently there was no association between ApoE4 and cardiovascular complications in elderly diabetic subjects, on the other hand, ApoE2 allele may have a protective role against cardiovascular complications. Our study showed that HDL was significantly lower in diabetic patients with cardiovascular compications in comparison to control group. The current study revealed that E4 allele was associated with dyslipidemia in diabetic patient without cardiovascular complications and healthy control but not in diabetic patient with cardiovascular complications.