86881:APOLIPOPROTEIN E (APOE)

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86881:APOLIPOPROTEIN E (APOE)
Alias Names: APO E Cardiac Risk
Methodology: Polymerase Chain Reaction/Fluorescence Monitoring (PCR/FM)
Edit Date: 6/11/2010
Performed: Monday, Thursday: Assay; Daily: DNA Isolation
Released: 2-7 days after setup at PeaceHealth Laboratories’ reference lab.
CPT Code: 83891-907A / 83896-907A x2 / 83898-907A / 83912-907A
Specimen Collection Details
Collection: One 4 mL lavender top tube (EDTA). Also acceptable: One 6 mL yellow top tube (ACD) Solution A or B.
Handling: Keep as whole blood. Refrigerate.
Stability: 72 hours ambient or 7 days refrigerated. Specimen unstable frozen.
Standard Volume: 3 mL whole blood.
Minimum Volume: 1 mL whole blood.
Transport: Refrigerated.
Comments: For assessment of cardiovascular disease only and should not be ordered for assessing Alzheimer disease in a demented patient. For Alzheimer’s assessment, order APOE Genotype (90475).
This test is not recommended for nonsymptomatic patients under 18 years of age.
Rejection Criteria: Serum; severely hemolyzed or frozen specimen.
This test may require insurance company prior authorization before ordering.
Please check the prior authorization list
.
Failure to gain preauthorization may result in denial of coverage.

Reference Range:
Homozygous apo e3 (e3/e3): This genotype is the most common (normal) genotype.
Background Information for Apolipoprotein E (APOE) 2 Mutations, Cardiovascular Risk

Characteristics: Hyperlipoproteinemia III (HPL III) is characterized by increased cholesterol and triglyceride levels, presence of B-VLDL, xanthomas, and premature vascular disease including coronary heart disease (CHD) and peripheral artery disease.

Incidence of HPL III: Approximately 1 in 5,000.

Inheritance: Autosomal recessive.

Penetrance: 1 to 5 percent of individuals homozygous for the E2 allele and 26 percent of those heterozygous for both E2 and familial hypercholesterolemia will develop symptoms.

Cause: The E2 isoform binds the lipoprotein receptors with only 2 percent of the affinity of E3 and E4 resulting in impaired clearance of chylomicron and VLDL remnants and increased plasma cholesterol and triglyceride levels.

Mutations Tested: E2, E3 (normal) and E4 alleles of the apolipoprotein E gene.

Clinical Sensitivity: About 5 percent of individuals with premature CHD are homozygous for E2.

Polymerase chain reaction (PCR) and fluorescence monitoring using hybridization probes.

Analytical Sensitivity and Specificity: 99 percent.

Limitations: Rare isoforms of APOE will not be detected. If rare alleles are suspected, phenotyping by isoelectric focusing may be indicated. Rare diagnostic errors can occur due to primer site muations.

Counseling and informed consent are recommended for genetic testing.