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HelpTest Code AD2ARSO PrecivityAD2, Reflex to Apolipoprotein E, Plasma
Additional Codes
Mayo Test Code: AD2AR
Ordering Guidance
This blood test is intended for use in patients aged 50 and older with signs or symptoms of mild cognitive impairment or dementia who are undergoing evaluation for Alzheimer disease or other forms of cognitive decline, and who have not had prior apolipoprotein E proteotyping or APOE genotyping.
Shipping Instructions
1. Specimens must be shipped frozen on dry ice.
2. Place labeled aliquot tubes inside a larger tube or vial for transport.
Specimen Required
Supplies: Screw cap micro tube, 2 mL, PCR Performance Tested, Low protein-binding (T983)
Collection Container/Tube: 10 mL Purple top (K EDTA)
Submission Container/Tube: Two 2-mL screw cap micro tubes
Specimen Volume: 3 mL in 2 tubes, each containing 1.5 mL
Collection Instructions:
1. Centrifuge within two hours of collection.
2. Label two 2-mL screw-cap micro tubes.
3. Aliquot 1.5 mL of plasma into each labeled micro tube.
4. Freeze plasma (no longer than 2 hours after collection) at or below -20° C.
Useful For
Assisting in the evaluation of adult patients, aged 50 years and older, with signs or symptoms of mild cognitive impairment or dementia who are being assessed for Alzheimer disease and other causes of cognitive decline
Determining APOE E4 status to aid in medical management and treatment decisions when the PrecivityAD2 blood test result is positive
This test is not intended for patients younger than 50 years, or for use as a screening test in patients without signs or symptoms of cognitive, or for serial testing for assessment of longitudinal changes.
Reflex Tests
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| C2NAP | Precivity-ApoE | No | No |
Testing Algorithm
When this test result is positive, then apolipoprotein E testing will be performed at an additional charge.
Method Name
Immunoprecipitation/Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS)
Reporting Name
PrecivityAD2 Reflex to ApoESpecimen Type
PlasmaSpecimen Minimum Volume
See Specimen Required
Specimen Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
| Plasma | Frozen | |
Reject Due To
| Gross hemolysis | Reject |
| Gross lipemia | Reject |
| Gross icterus | Reject |
| Outside of age range Specimen collected outside of testing range (too long in storage before arrival to testing facility) Insufficient volume Incorrect labeling |
Reject |
Reference Values
Amyloid Probability Score 2 (APS2) (range of 0-100):
Negative: 0-47
Positive: 48-100
Abeta42/40 Ratio:
≥0.095 Consistent with absence of amyloid plaques
Percent p-tau217:
<4.2% consistent with absence of brain amyloid plaques
ApoE Proteotype
E2/E2, E2/E3, E2/E4, E3/E3, E3/E4, E4/E4
-E3 is the most common allele.
-E4 allele is associated with increased risk of amyloid plaques.
-E2 allele is associated with lower risk of amyloid plaques.
Cautions
This test is not a standalone test; positive or negative Amyloid Probability Score 2 (APS2) values alone neither rule in nor rule out a diagnosis of Alzheimer disease (AD).
Test results should be used in conjunction with other diagnostic tools such as neurological examination, neurobehavioral tests, imaging, and routine laboratory tests.
False-positive and false-negative test results may occur.
This test uses interpretive data that were derived from clinical studies in a predominantly White US population of patients with mild cognitive impairment or early dementia. The extent of the differences in results (if any) based on individuals of other racial and ethnic groups has not yet been firmly established.
Currently, there is insufficient evidence to support serial testing for the assessment of longitudinal changes in biomarkers, including monitoring response to therapy.
The results of other analyte tests using other methodologies cannot be interpreted in the context of the PrecivityAD2 test.
Apolipoprotein E
This test detects only peptides from E2, E3 and E4 proteins and does not detect peptides from rare apolipoprotein E (ApoE) phenotypes.
Although multiple epidemiological studies of diverse ethnic populations have demonstrated increased frequency of the E4 allele in late-onset AD cohorts, the extent of differences in individual risk estimates across different ethnicities has not been established.(22)
The E4 allele is neither necessary nor sufficient for the development of AD; thus, ApoE isoform/APOE allele status cannot be used alone for the diagnosis of AD.(18)
Day(s) Performed
Monday through Friday
Report Available
18 days post sample receipt from MCLSpecimen Retention Time
60 daysPerforming Laboratory
C2N Diagnostics LLCTest Classification
C2N Diagnostics has developed and determined the analytical and clinical validity performance characteristics of this Laboratory Developed Test (LDT). This assay has been validated pursuant to CLIA regulations and is used for clinical purposes. This assay has not been cleared or approved by the FDA.CPT Code Information
0503U
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| AD2AR | PrecivityAD2 Reflex to ApoE | Not Provided |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| C2RG | Amyloid Probability Score 2 (APS2) | Not Provided |
| C2RGF | APS2 Result | Not Provided |
| C2RH | APS2 Result Interpretation | Not Provided |
| C2RI | APS2 Result Reference Interval | Not Provided |
| C2RJ | APS2 Description | Not Provided |
| C2RK | Percent p-tau217 | Not Provided |
| C2RL | Percent p-tau217 Reference Interval | Not Provided |
| C2RLD | Percent p-tau217 Description | Not Provided |
| C2RM | Abeta42/40 Ratio | Not Provided |
| C2RN | Abeta42/40 Ratio Reference Interval | Not Provided |
| C2RND | Abeta42/40 Ratio Description | Not Provided |
| C2RO | Test Description | Not Provided |
| C2RP | Limitations of Test Result | Not Provided |
| C2RQ | Methods and Assay Category | Not Provided |
| C2RR | References | Not Provided |
| C2RRC | Report Comment | Not Provided |
| C2RRF | Performing Site | Not Provided |
Forms
If not ordering electronically, complete, print, and send a Neurology Specialty Testing Client Test Request (T732) with the specimen.