RESUMO
BACKGROUND: The aim of this study was to investigate the association of apolipoprotein B gene polymorphisms with coronary artery disease and lipid levels in Indians. METHODS AND RESULTS: One hundred patients of angiographically proven atherosclerotic coronary artery disease and one hundred age- and sex-matched control subjects (treadmill negative) were included in the study. Serum lipids including cholesterol, triglycerides, high-density lipoprotein, low-density lipoprotein, very low-density lipoprotein, and apolipoprotein B were analyzed. Genomic DNA was extracted and the apolipoprotein B 3' hypervariable region amplified by polymerase chain reaction. Regions carrying Xba1, EcoR1, and Msp1 restriction sites present in the apolipoprotein B gene were amplified and digested separately by the respective enzymes. Restriction fragment length polymorphism analysis showed that EcoR1 with the R+/R+ genotype was significantly more common in patients with coronary artery disease. Overall, the genotypes EcoR1+/+, Msp1+/+, Xba1+/+ and Eco R1+/+ Msp1+/-, Xba1-/- were significantly more common in patients as compared to controls (p<0.05). When gene polymorphisms were compared with lipid abnormalities, the genotypes EcoR1+/+, Xba1-/-, and Msp1+/+ were more frequent in patients with elevated apolipoprotein B and very low-density lipoprotein levels. On the other hand, these genotypes were less common in patients with increased total cholesterol and low-density lipoprotein levels. When we studied the individual alleles of the variable number of tandem repeats region, we observed that allele 34 was significantly increased in patients with coronary artery disease as compared to controls. Allele 36 was present with a frequency of 1% in controls while it was totally absent in patients. CONCLUSIONS: This study identifies the apolipoprotein B gene polymorphism associated with coronary artery disease. An association between apolipoprotein B gene polymorphisms and elevated apolipoprotein B and very low-density lipoprotein levels was observed. However, there was no positive association with other elevated lipid levels in North Indians from Uttar Pradesh.