Detection of the apoB-3500 mutation (glutamine for arginine) by gene amplification and cleavage with MspI.

A single primer-template mismatch 2 bp from the apoB-3500 (G to A) mutation permits introduction of a cleavage site for MspI (C/CGG) in normal alleles but not in mutant alleles (CCAG). After amplification, cleavage, and polyacrylamide gel electrophoresis, normal and mutant alleles could be unambiguously distinguished. We constructed a positive (homozygous mutant) standard by site-directed mutagenesis. A negative standard was DNA from a homozygous normal subject. The method enables us to screen for the mutation with 12 microliters of spotted whole blood as the source of DNA.