Polymorphisms XbaI (rs693) and EcoRI (rs1042031) of the ApoB gene are associated with carotid plaques but not with carotid intima-media thickness in patients with diabetes mellitus type 2

Abstract

Background: Apolipoprotein B is a key structural component of all the atherogenic lipoproteins (LDL, VLDL and IDL). Genetic variations of the ApoB gene may affect plasma ApoB and lipid levels, thus influencing atherogenesis. The present study was designed to investigate the association of polymorphisms XbaI (rs693) and EcoRI (rs1042031) of the ApoB gene with plasma ApoB level, lipid levels and the different ultrasound phenotypes of carotid atherosclerosis in patients with diabetes mellitus type 2. Patients and methods: 595 patients with diabetes (399 on statin therapy and 196 without) and 200 healthy controls were enrolled in the study. The carotid intima-media thickness (CIMT) and plaque characteristics (presence and structure) were assessed ultrasonographically. Biochemical analyses were performed using standard biochemical methods. Both XbaI (rs693) and EcoRI (rs1042031) genotypes were determined by real-time PCR. Results: Genotype distributions and allele frequencies of the XbaI and EcoRI polymorphisms were not statistically significantly different between diabetic patients and controls. No statistically significant difference in lipid parameters, ApoA1, ApoB, hs-CRP and fibrinogen as well as CIMT was observed in diabetic patients regarding XbaI and EcoRI polymorphisms, even after adjustment for statin treatment. The risk of having plaques on carotid arteries was higher in homozygous carriers of the mutant X + allele (OR = 1.74, p = 0.03) and lower in diabetics carrying mutant E- alleles (OR = 0.48, p = 0.02). Neither XbaI nor EcoRI polymorphism was associated with CIMT or presence of unstable plaques in diabetic patients. Plasma ApoB level was not independently associated with any of the ultrasonographic parameters of carotid atherosclerosis. Conclusions: Both XbaI and EcoRI polymorphisms were associated with presence of plaques on carotid arteries but not with CIMT or presence of unstable plaques. Plasma ApoB level was not independently associated with ultrasonographic phenotypes of carotid atherosclerosis in patients with diabetes mellitus.