Polymorphism of apolipoprotein E influences levels of serum apolipoproteins E and B in the human neonate.

To gain more insight into the genetic vs. environmental influence of the apoE phenotypes on plasma lipoprotein variation we studied human umbilical cord sera at birth. Apolipoprotein E genetic phenotypes were determined in 110 individuals by immunoblotting and shown to be identical to the adult human isoforms with six phenotypes present and occurring at a similar frequency as reported previously for the adult population in the same area. Total serum cholesterol and triglyceride levels were low in the neonates and did not differ significantly between apoE phenotypes. On the other hand as in the adult, levels of apoE and B differed significantly between the phenotypes. ApoE was highest in individuals with the epsilon 2 allele and lowest in individuals expressing apoE4, and vice versa for apoB. We conclude that apoE phenotypes in human umbilical cord blood serum are already associated with pronounced differences in apoE and B levels in the newborn. The study demonstrates that the association of apoE and apoB levels with the apoE polymorphism occurs independently of significant enteral nutrition in the relatively constant in utero environment.