Effect of apolipoprotein E (apoE) phenotype on the apoE content of CSF-HDL in children.

BACKGROUND

The majority of the lipoprotein in cerebrospinal fluid (CSF) is apolipoprotein E (apoE)-containing HDL. Since neuronal cells express lipoprotein receptors which recognize apoE, apoE in CSF-HDL is believed to be important for the development of central nervous system (CNS) in children. In adults, the apoE phenotype affects the plasma apoE concentration and the epsilon 4 allele is a risk factor for Alzheimer's disease. Due to the requirement for CNS development, we examined whether the apoE phenotype affects the composition and concentration of CSF-HDL in children.

METHODS

We determined the apoE phenotype in 107 neurologically normal subjects, including 67 children (<20 years), by isoelectronic focusing. We also measured apoE, total cholesterol (TC), and phospholipid (PL) concentrations in the CSF.

RESULTS

The respective frequencies of apoE4/3, E3/3 and E3/2 were 16.4%, 77.6%, and 6.0%. The allele frequencies of epsilon 4, epsilon 3, and epsilon 2 were 0.082, 0.888, and 0.030, respectively. There were no significant differences in the CSF-apoE, TC, or PL concentrations or the apoE/PL ratio among the apoE phenotypes. However, the CSF-apoE/PL ratio was significantly higher in children than in adults.

CONCLUSION

The apoE phenotype does not affect the composition or concentration of CSF-HDL in children. We speculate that an apoE4 carrier is prevented in childhood from the impaired development of central nervous system by CSF-HDL enriched with apoE.