Background: High-density lipoprotein (HDL) consists of apolipoprotein E (apoE)-rich and apoE-poor HDL particles. ApoE-rich HDL level is high at birth, but decreases after birth with reciprocal elevation in low-density lipoprotein (LDL)-cholesterol.

Objectives: To clarify whether apoE-rich HDL decreases after birth in children with familial hypercholesterolemia (FH), a disorder caused by impaired LDL clearance.

Methods: We measured apoE-rich HDL-cholesterol and LDL-cholesterol during the first year of life in 10 FH children (1 homozygote and 9 heterozygotes), 12 non-FH siblings, and 75 healthy controls.

Results: At birth, apoE-rich HDL-cholesterol was undetectable in a homozygous FH child, and lower in heterozygous FH children than in non-FH siblings and controls (4 ± 2 vs. 12 ± 4 and 11 ± 4 mg/dl, p<0.001). At 3–4 months, apoE-rich HDL-cholesterol increased in homozygous and heterozygous FH children, and decreased in non-FH siblings and controls. At 12 months, apoE-rich HDL-cholesterol levels were similar among these 4 groups (6–7 mg/dl). In contrast, LDL-cholesterol concentration was always twice as high in heterozygous FH children as in non-FH siblings and controls (at birth, 50 ± 15, vs. 25 ± 7 and 25 ± 5 mg/dl, p<0.001; at 3–4 months of age, 159 ± 29, vs. 71 ± 16 and 73 ± 15 mg/dl, p<0.001; at 12 months of age, 156 ± 29, vs. 75 ± 18 and 76 ± 17 mg/dl, p<0.001).

Conclusion: ApoE-rich HDL level is low at birth in FH children, and increases to the normal level in the first year of life, opposite to the change in normal children.