Apolipoprotein E polymorphism in an Iranian hypercholesterolemic population

Apolipoprotein E [apo E] is a structural constituent of several serum lipoprotein classes. It plays an important role in lipid metabolism by acting as a ligand for low-density lipoprotein [LDL] and chylomicron remnant receptors. Three common alleles called epsilon 2, epsilon 3 and 4 have been described, which code for three protein isoforms [E2, E3 and E4]. The polymorphism is clinically significant, and it has therefore become very important in epidemiological studies attempting to obtain complete information about apo E allele frequencies in populations around the world. In the present study, two point mutations coding amino acid residues 112 and 158 were amplified using the polymerase chain reaction [PCR] from DNA extracted from 100 Iranian subjects. Apo E genotypes were determined by restriction fragment length polymorphism [RFLP] and allelic frequencies were estimated by gene counting [epsilon 2 = 0.01, epsilon 3 = 0.88, epsilon 4 = 0.11]. The Hardy-Weinberg expectation of genotype distribution was calculated from the estimated allele frequencies and a chi 2-test was used to test for equilibrium [chi 2 = 0.487, P>0.05]. Student's t-test indicated that subjects with the two most common apo E genotypes [E4/E4, E3/E3] were different from each other in means serum total cholesterol [t = 3.1, P<0.01]. Allele frequencies of the present study performed on Iranian subjects were similar to those of Japanese, Korean [Asian groups] Mexican and African American populations