THE APOLIPOPROTEIN-E PHENOTYPE HAS A STRONG INFLUENCE ON TRACKING OF SERUM-CHOLESTEROL AND LIPOPROTEIN LEVELS IN CHILDREN - A FOLLOW-UP-STUDY FROM BIRTH TO THE AGE OF 11 YEARS

The extent to which an individual maintains his position relative to t he rest of the population is called tracking. The objective of this st udy was to examine the effect of the apolipoprotein E (apoE) phenotype on the tracking of serum cholesterol and lipoproteins from birth to t he age of 11 y. In a longitudinal follow-up study of healthy children, concentrations of total serum cholesterol and triglyceride were deter mined at birth (n = 193), and at the ages of 2 (n = 192), 4 (n = 192), 6 (n = 190), 9 (n = 188), and 12 mo (n = 196), and 5 (n = 162) and 11 y (n = 153). Concentrations of total HDL, HDL2, and HDL3, VLDL, and L DL cholesterol were determined at 2, 6, 9, and 12 mo (n = 36), and 5 ( n = 162) and 11 y (n = 153). The apoE phenotype was determined in 151 children. The children had the following apoE phenotypes: 4 had type 4 /4 and 40 type 3/4 (group apoE4), 94 had type 3/3 (group apoE3), and 1 1 had type 2/3 and 2 type 2/4 (group apoE2). The correlation coefficie nts for total cholesterol levels during childhood compared with the le vel at 11 y of age were: 0.03 at birth, 0.26 (p < 0.001) at 2 mo, 0.24 (p < 0.001) at 4 mo, 0.24 (p < 0.001) at 6 mo, 0.28 (p < 0.001) at 9 mo, 0.41 (p < 0.001) at 12 mo, and 0.60 (p < 0.001) at 5 y. When the c hildren were divided into three groups according to their apoE phenoty pes, these three groups had the following correlation coefficients at 4 mo, 12 mo, or 5 y of age compared with the level at the age of 11 y; group apoE2: r = 0.65 (p < 0.01), r = 0.59 (p < 0.01), and r = 0.72 ( p < 0.01); group apoE3: r = 0.27 (p < 0.01), 0.43 (p < 0.001), and r = 0.64 (p < 0.001); and group apoE4: r = 0.14 (p = NS), r = 0.33 (p < 0 .05), and 0.42 (p < 0.01). The apoE phenotype also strongly influenced the tracking of the LDL cholesterol levels; the correlation coefficie nts between 5 and 11 y of age were for group apoE2 r = 0.84 (p < 0.001 ), for group apoE3 r = 0.70 (p < 0.001), and for group apoE4 r = 0.37 (p < 0.05). Our results indicate that the apoE phenotype strongly infl uences the tracking of lipids. The children having apoE 2/3, 2/4, and 3/3 phenotypes maintained their relative cholesterol and lipoprotein l evels better than the others throughout the first 11 y of age. Because the apoE phenotype strongly affects the tracking of serum cholesterol , the usefulness of cholesterol screening in predicting future cholest erol values should be analyzed, keeping the apoE phenotype in mind.