Apolipoprotein E Polymorphism in an Iranian Hypercholestrolemic 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 e2, e3 and e4 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 (e2 = 0.01, e3 = 0.88, e4 = 0.11). The Hardy-Weinberg expectation of genotype distribution was calculated from the estimated allele frequencies and a c2-test was used to test for equilibrium (c2 = 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.