Genotyping compared with protein phenotyping of the common apolipoprotein E polymorphism

Area of Science:

• Genetics
• Biochemistry
• Molecular Biology

Background:

• Apolipoprotein E (apo E) plays a crucial role in lipid metabolism and is associated with various diseases.
• Accurate determination of apo E genotypes is essential for genetic epidemiological studies.

Purpose of the Study:

• To compare the accuracy of polymerase chain reaction (PCR) based genotyping with isoelectric focusing (IEF) for determining apolipoprotein E (apo E) genotypes.
• To assess the reliability of current methods for apo E genotype analysis in a large cohort.

Main Methods:

• Genotyping of 460 Danish men using PCR to amplify a specific DNA fragment.
• Restriction endonuclease cleavage of the amplified fragment to identify polymorphic sites.
• Comparison of PCR-derived genotypes with phenotypes determined by isoelectric focusing (IEF) and immunoblotting.

Main Results:

• A high degree of concordance was observed between PCR genotyping and IEF phenotyping (98.0%).
• Discrepancies in 9 cases (2.0%) were primarily attributed to technical issues with IEF ('faint bands') or potentially rare mutations.
• The findings support the reliability of PCR-based methods for apo E genotyping.

Conclusions:

• Polymerase chain reaction (PCR) is a reliable and accurate method for determining apolipoprotein E (apo E) genotypes.
• The study provides reassurance regarding the validity of genetic epidemiological studies utilizing apo E genotyping.
• Potential sources of error in IEF-based phenotyping were identified, highlighting the importance of method validation.