Apolipoprotein E polymorphism in the Tunisian population:: Frequency and effect on lipid parameters

Objectives: We determined the frequencies of apolipoprotein E (apo E) gene alleles and examined the association between apo E polymorphism and lipid parameters in a sample of the Tunisian population. Design and methods: Apo E polymorphism was investigated using PCR, and plasma lipid parameters were measured in 122 men and 111 women aged 35 to 87 years. Results: The allele frequencies were epsilon 2: 7.3%, epsilon 3: 84.6%, and epsilon 4: 8.1%. Apo E polymorphism was associated with significant differences (P < 0.001) in total cholesterol, apo B and LDL cholesterol in both men and women. epsilon 2 carriers had the lowest mean total cholesterol, apo B and LDL-C concentrations, and subjects with the epsilon 4 allele had the highest levels. Triglycerides levels increased with the epsilon 4 allele, but this did not reach statistical significance. These results remained unchanged after adjustment for age, body mass index, sex, hypertension, diabetes and smoking. However, in obese subjects (BMI > 30 k g/M-2), TG concentrations were significantly lower in individuals homozygous for the epsilon 3 allele compared to those with the alleles epsilon 2 or epsilon 4. Conclusion: In this sample of the Tunisian population, the distribution of apo E gene alleles is similar to that observed in Southern European populations with low prevalence of the epsilon 4 allele. Variations in the apo E gene play a role in determining plasma lipid levels. These data also suggest that effects of apo E alleles on lipids levels are partly dependent on environmental variables such as BMI. These findings highlight the importance of the gene/environment interaction on the deleterious effect of obesity on cardiovascular risk factors. (c) 2006 The Canadian Society of Clinical Chemists. All rights reserved.