Apolipoprotein E gene polymorphisms in patients with premature myocardial infarction: a case-controlled study in Asian Indians in North India

Objectives: Several factors, including abdominal obesity, insulin resistance, diabetes mellitus and low levels of high-density lipoprotein cholesterol have been implicated in the high prevalence and early onset of coronary heart disease in Asian Indians. However, there are no reports regarding the role of apolipoprotein E (apo E) gene polymorphisms in premature myocardial infarction (MI) in this population. This study aimed to study the role of apo E gene polymorphisms in premature MI patients and their relation to serum lipid levels. Design and methods: Apo E gene polymorphisms were analysed in 35 patients with MI aged <40 years and in 45 age- and sex-matched controls using polymerase chain reaction-restriction fragment length polymorphism. Levels of serum lipids were measured in addition to the evaluation of conventional risk factors. Results: Higher frequencies of the apo E4 allele (P<0·0001) and of genotypes E3/E4 (P<0·005) and E4/E4 (P<0·005) were recorded in the premature MI group compared with the controls. Multivariate regression analysis revealed that, after adjusting for other covariates, individuals with the E4 allele were at ~46 times higher odds to develop premature MI compared with individuals without the E4 allele adjusted odds ratio, OR (95% confidence interval, CI): 45·7 (4·9-421·3). Among conventional risk factors, higher risk was observed in those having dyslipidaemia OR (95% CI): 8·7 (0·9-86·6) and those with a high waist : hip ratio OR (95% CI): 5·6 (1·4-21·2). Conclusion: Based on the robust association, the apo E4 allele should be considered as an independent risk factor for premature MI in Asian Indians.