Serum apolipoprotein E concentrations among Turks: information additive to genotype relative to dyslipidemia and metabolic syndrom

OBJECTIVES
We investigated the relationship of serum apolipoprotein E (apoE) levels with dyslipidemia and metabolic syndrome (MS) in the general population and their degree of independence of the apoE genotype.

STUDY DESIGN
This cross-sectional study included a random sample of Turkish adults whose serum apoE concentrations were measured. Metabolic syndrome was defined with the ATP-III criteria with modification for male abdominal obesity.

RESULTS
Of 454 participants (222 men, 232 women; mean age 54.1±9.6 years), the median serum apoE concentration was 3.93 mg/dl with an interquartile range of 1.75 to 5.82 mg/dl. Higher apoE concentrations were found in male carriers of the ε4 allele than homozygous ε3 subjects. Multivariate analysis showed the apoE genotype (grouped into 3) as a determinant of apoE levels, and serum apoB levels as a major covariate. In logistic regression analysis, doubling of the apoE level showed significant associations, independent of the apoE polymorphism, with total cholesterol, elevated apoB (OR 4.54, 95% CI 2.83; 12.3) and triglyceride/HDL-cholesterol dyslipidemia (OR 2.82, 95% CI 1.67; 5.18). Doubling of the apoE level was also associated in both genders with MS (OR 1.72, 95% CI 1.24; 2.38), after adjustment for confounders.

CONCLUSION
ApoE concentrations in Turkish adults are significantly linked to serum total cholesterol, hyperapoB, and atherogenic dyslipidemia, independent of the apoE polymorphism. They are also significantly and independently associated with MS. Male carriers of the ε4 allele have no lower apoE concentrations than homozygous ε3 individuals, suggesting a close link between apoE and apoB levels.