Application of denaturing gradient gel electrophoresis to detect DNA sequence differences encoding apolipoprotein E isoforms.

Apolipoprotein E (apoE) plays an important role in plasma lipid metabolism. Three common isoforms of this protein have been identified by the isoelectric focusing method. In this report we describe a new method for distinguishing these isoforms. Our method employs PCR amplification of the DNA sequence of exon 4 in the apoE gene followed by denaturing gradient gel electrophoresis (DGGE) to distinguish its different melting characteristics. Identification of the ApoE isoforms through DNA melting behavior rather than protein charge differences eliminates the problems associated with isoelectric focusing and facilitates screening for additional mutations at the apoE locus.