Analysis of apolipoprotein E genotypes by the Amplification Refractory Mutation System

The Amplification Refractory Mutation System (ARMS) has been successfully applied to the detection of apolipoprotein (apo) E genotypes in human DNA extracted from peripheral blood. By using four allele-specific oligonucleotide primers and one common primer, one can identify the three common alleles of the apo E genetic polymorphism, epsilon 2, epsilon 3, and epsilon 4. The system amplifies two sequences of the apo E gene, one of 181 bp and the other 319 bp. These sequences are amplified when DNA containing a particular allele is incubated with its allele-specific oligonucleotide primer and a common primer. The method is simple, reliable, and nonisotopic and obviates the need for digestion with restriction endonucleases or for hybridization with allele-specific oligonucleotide probes. Genotyping DNA by this method overcomes the problem of post-translational modification of the apo E phenotype encountered with isoelectric focusing of the mature plasma apo E protein.