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Apolipoprotein E phenotyping: a word of caution.
P R Wenham1, A Sedky, R J Spooner
1Department of Clinical Chemistry, Western General Hospital, Edinburgh, UK.
Annals of Clinical Biochemistry
|November 1, 1991
Summary
Genotyping is more accurate than phenotyping for determining apolipoprotein E status, especially in diabetes patients. Isoelectric focusing may lead to errors in apolipoprotein E phenotype assignment.
Area of Science:
- Genetics
- Biochemistry
- Molecular Biology
Background:
- Apolipoprotein E (ApoE) gene variations influence lipid metabolism and disease risk.
- Accurate determination of ApoE genotype is crucial for understanding its role in various conditions, including diabetes.
Purpose of the Study:
- To compare the accuracy of phenotyping and genotyping methods for assessing allelic variation at amino acids 112 and 158 of the apolipoprotein E gene locus.
- To evaluate the reliability of isoelectric focusing compared to DNA analysis for ApoE status determination in individuals with and without insulin-dependent diabetes.
Main Methods:
- Phenotyping using isoelectric focusing and immunoblotting of plasma.
- Genotyping using polymerase chain reaction amplification, CfoI restriction digestion, and polyacrylamide gel electrophoresis.
Main Results:
- Discrepancies between phenotype and genotype were observed in 15% of all individuals studied (13% in diabetics, 17% in controls).
- Isoelectric focusing demonstrated potential for erroneous apolipoprotein E phenotype assignment, even after neuraminidase treatment.
Conclusions:
- Genotyping via DNA analysis is the preferred method for determining apolipoprotein E status due to higher accuracy.
- Phenotyping methods like isoelectric focusing may not be sufficiently reliable for precise ApoE genotyping.