human apolipoprotein e ( apoe ) exists in the population in three common genetically determined isoforms , apoe-2 , e-3 , and e-4 , that are coded for by three alleles epsilon-2 , epsilon-3 and epsilon-4 at the apoe structural gene locus resulting in six phenotypes , three homozygotes ( e 2/2 , e 3/3 , and e 4/4 ) and three heterozygotes ( e 2/3 , e 2/4 , and e 3/4 ) .
C0003595
apolipoprotein e
C0052198
apoe-2