Apolipoprotein E Mutation Detection for Cardiovascular Risk


Sunquest Code:APOECV  
Epic Code:LAB6885Epic Name:Apolipoprotein E Genotype CV Risk
Methodology:Polymerase chain reaction/fluorescence monitoring
Turnaround Time:Specimens are sent to reference laboratory Mon-Sat; results are reported in 2-7 days.
Compliance:

The performance characteristics of this test were validated by ARUP Laboratories, Inc. The U.S. Food and Drug Administration (FDA) has not approved or cleared this test. However, FDA approval or clearance is currently not required for clinical use of this test. The results are not intended to be used as the sole means for clinical diagnosis or patient management decisions. ARUP is authorized under Clinical Laboratory Improvement Amendments (CLIA) and by all states to perform high-complexity testing.



Collection Instructions

Specimen:Blood
Optimal Volume:3 mL
Minimum\Peds Volume:1 mL
Container:Purple (EDTA) (Yellow (ACD, Solution A) tube available from laboratory)
Causes for Rejection:Serum or plasma. Heparinized specimens.


Processing and Shipping

Specimen Processing:Aliquot 3 mL, 1 mL minimum whole blood. Store in refrigerator.
Shipping Instructions:Ship at refrigerated temperature.
Stability:Stability: 72 hours at room temperature; 2 weeks refrigerated; 1 month frozen.
Test Performed at or Referral Lab Lab Sendouts  (ARUP)
Referral Lab number:2013337


Interpretive

Reference Range:

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

 

The apo E gene has three common alleles (e2, e3, e4) that code for thee isoforms of the apo E protein (E2, E3, E4). The alleles are inherited co-dominantly resulting in six genotypes (e2/e2, e2/e3, e2/e4, e3/e3, e3/e4, e4/e4). Both apo E2 and E4 are associated with higher plasma triglyceride concentrations, but only E2 has been associated type III hyperlipoproteinemia. Over 95% of individuals with type III hyperlipoproteinemia have the 2/2 genotype; although in rare cases, individuals with a single e2 allele may also have symptoms. Only 1-6% of individuals with 2/2 genotype will show symptoms; therefore, other genetic and environmental factors must contribute to the phenotypic expression of the disease. The e4 allele is associated with increased plasma cholesterol levels and therefore an increased risk for coronary heart disease.

 

Although apo E genotypes are associated with hyperlipoproteinemia, they are not sufficient for diagnosis of these disorders. The results must be interpreted within the context of the appropriate clinical setting and in association with other laboratory data. Rare isoforms of apo E will not be detected. If rare alleles are suspected, phenotyping by isoelectric focusing may be indicated.

 

Patient DNA is assayed for point mutations in codons 112 and 158 of the apolipoprotein E gene by the polymerase chain reaction (PCR) and the fluorescence monitoring using hybridization probes.  Sensitivity and specificity for detection of these mutations are 99.9%.

 

Due to the unique nature of genetic testing, patients should receive pre and post test counseling.  Informed consent is recommended. Consent forms are available from ARUP upon request or online at www.aruplab.com.

 

 

Limitations:This test is for cardiovascular risk assessment only and must not be ordered for assessing Alzheimer disease in a demented patient. Athena Neurosciences, Inc. is the exclusive licensee of U.S. Patent No. 5,508,167 for the Alzheimer risk assessment. This test is not recommended for nonsymptomatic patients under 18 years of age.


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