Apolipoprotein E (apo E) plays a role in the regulation of the lipid metabolism 
of humans. Apo E, 229 amino acid polypeptide, is classified into three major 
isoform (E2, E3, E4) according to the differences of amino acid in position 112 
and 158. In the normal population apo E3 isoform is most prevalent and apo E2 or 
E4 is frequently associated with hyperlipoproteinemia. To find out the frequency 
of apo E isoform distribution in the Korean population, apo E genotyping was 
performed. After amplification of apoE gene by polymerase chain reaction (PCR), 
restriction isotyping was done by cleavage with restriction enzyme Hha I and 
polyacrylamide gel electrophoresis. The apo E allele frequency in 73 normal 
subjects was 4.8% for E2, 84.9% for E3 and 10.3% for E4. In diabetic patient 
with hyperlipoproteinemia, the frequency of apo E allele was 6.3% for E2, 81.0% 
for E3 and 12.7% for E4. There was no significant difference in apo E isoform 
distribution between diabetics and normal populations. But in patients with 
cardiovascular disease with hyperlipidemia, the apo E4 allele frequency was 
significantly higher than normal (20.0% vs 10.3%, p < 0.005). Apo E3 was the 
most common isoform in normal and diabetic subjects and apo E2 isoform was 
rather low frequency compared to Caucasians. This pattern is similar to the 
Japanese population but somewhat different from other populations. From the data 
of a high association of apo E4 allele and cardiovascular disease with 
hypercholesterolemia, apo E isoform may be one of the determinants of 
hyperlipoproteinemia. The PCR method may be useful in apo E genotyping.