Ordering Recommendation

Use to provide supporting evidence for a diagnosis of type III hyperlipoproteinemia for evaluation of premature coronary heart disease.

Mnemonic
APOE CR
Methodology

Polymerase Chain Reaction/Fluorescence Monitoring

Performed

Mon, Thu

Reported

2-7 days

New York DOH Approval Status
This test is New York DOH approved.
Specimen Required
Patient Preparation
Collect

Lavender (EDTA), Pink (K2EDTA), or Yellow (ACD Solution A or B).

Specimen Preparation

Transport 3 mL whole blood. (Min: 1 mL)

Storage/Transport Temperature

Refrigerated.

Unacceptable Conditions

Plasma or serum. Heparinized specimens.

Remarks

This test is not recommended for nonsymptomatic patients under 18 years of age.

Stability

Ambient: 72 hours; Refrigerated: 2 weeks; Frozen: 1 month

Reference Interval

Homozygous APOE e3 (e3/e3): This genotype is the most common (normal) genotype.

Interpretive Data

Background Information for Apolipoprotein E (APOE) Genotyping, 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 of HPL III:
Multifactorial; greater than 90 percent of affected individuals are homozygous for the e2 allele but other factors such as diabetes and hypothyroidism also play a large role in development of disease. 
Penetrance:
1 to 5 percent of individuals homozygous for the e2 will develop HPL III.
Cause:
2 copies of the e2 allele provides supporting evidence for a diagnosis of HPL III in a symptomatic individual but e2 homozygosity is neither necessary nor sufficient for HPL III.
Variants Tested:
 APOE gene alleles, e2 (c.388T, p.130Cys and c.526C>T, p.Arg176Cys), e3 (c.388T, p.130Cys and c.526C, p.176Arg ), e4 (c.388T>C, p.Cys130Arg and c.526C, p.176Arg).
Clinical Sensitivity: 90 percent of individuals with HPL III are homozygous for the e2 variant.
Methodology:
Polymerase chain reaction (PCR) and fluorescence monitoring using hybridization probes.
Analytical Sensitivity and Specificity:
99 percent.
Limitations:
Only the e2, e3 and e4 variants will be detected. Rare isoforms of APOE will not be detected. If rare alleles are suspected, phenotyping by isoelectric focusing may be indicated. Diagnostic errors can occur due to rare sequence variations.

Compliance Category

Laboratory Developed Test (LDT)

Note
Hotline History
N/A
CPT Codes

81401

Components
Component Test Code* Component Chart Name LOINC
2013338 APOE Specimen 31208-2
2013339 APOE Cardiovascular Risk, Genotype 34438-2
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the Interface Map.
Aliases
  • APOE
  • ApoE 2 mutations
  • ApoE cardiac risk
  • ApoLipoprotein E Genotype
Apolipoprotein E (APOE) Genotyping, Cardiovascular Risk