Background: Apolipoprotein E (apoE) phenotype is a genetic determinant of plasma total cholesterol and low density lipoprotein (LDL) cholesterol concentrations, that are classical coronary heart disease risk factors. ApoE appears in three major isoforms E2, E3, and E4, coded by corresponding alleles epsilon 2, epsilon 3, and epsilon 4. These give rise to six different phenotypes.
Objective: To study the associations of apoE phenotype with cord serum lipids (during minimal enteral nutrition), and with serum lipids of 3-year-old children.
Subjects and methods: We determined serum lipid levels and apoE phenotypes in 206 newborns and 259 3-year-old children in connection with a larger follow-up study of atherosclerosis precursors in children and young adults. ApoE phenotyping was done directly from plasma by isoelectric focusing followed by immunoblotting.
Results: The effect of apoE phenotype on serum total and LDL cholesterol was significantly different in newborns and 3-year-old children (two-way ANOVA, interaction between apoE phenotype and age group: P < .001 for both). In 3-year-old children, the concentrations of serum total cholesterol and LDL cholesterol increased with apoE phenotype in the order of E3/2, E3/3, E4/3, and E4/4, in both males and females (P < .0001). On the contrary, in neonates total cholesterol and LDL cholesterol concentrations were low and did not differ significantly between apoE phenotypes (P > .05) either in males or in females. The mean serum levels of triglycerides and high density lipoprotein cholesterol did not differ between apoE phenotypes either in 3-year-old children or newborns.
Conclusions: The results show that the differences in serum total and LDL cholesterol levels between apoE phenotypes are formed after birth by the influence of environmental factors and suggest that both genetic and external factors influence the levels of serum cholesterol concentrations during the first years of life.