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HelpTest Code JAKXB JAK2 Exon 12 and Other Non-V617F Mutation Detection, Blood
Additional Codes
CNE Order Code: JAK2Exon12
Reporting Name
JAK2 Exon 12 Mutation Detection, BUseful For
Second-order testing to aid in the distinction between a reactive cytosis and a myeloproliferative neoplasm, particularly when a diagnosis of polycythemia is being considered, using blood specimens
Testing Algorithm
This is a second-order test that should be used when the test for the JAK2B / JAK2 V617F Mutation Detection, Blood test is negative. The sensitivity of this assay is much less than that of the JAK2B test. This is because the sequencing technique is required to evaluate for many potential mutations. The sensitive JAK2B test should always be performed first, as the JAK2 mutation burden may be very low in some specimens. If the JAK2B test is negative, then this assay should be performed for detection of non-V617F JAK2 mutations.
For more information see:
-Myeloproliferative Neoplasm: A Diagnostic Approach to Peripheral Blood Evaluation
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Specimen Type
Whole bloodOrdering Guidance
In all cases being evaluated for JAK2 mutation status, the initial test that should be ordered is JAK2B / JAK2 V617F Mutation Detection, Blood, a sensitive assay for detection of the mutation. However, if no JAK2 V617F mutation is found, further evaluation of JAK2 may be clinically indicated.
Additional Testing Requirements
Shipping Instructions
Specimen must arrive within 5 days (120 hours) of collection. Collect and package specimen as close to shipping time as possible.
Necessary Information
Date of collection is required.
Specimen Required
Container/Tube:
Preferred: Lavender top (EDTA)
Acceptable: Yellow top (ACD)
Specimen Volume: 10 mL
Collection Instructions:
1. Invert several times to mix blood.
2. Send whole blood specimen in original tube. Do not aliquot.
Specimen Minimum Volume
8 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Whole blood | Refrigerated (preferred) | 5 days | PURPLE OR PINK TOP/EDTA |
| Ambient | 5 days | PURPLE OR PINK TOP/EDTA |
Special Instructions
Reference Values
An interpretive report will be provided.
Day(s) Performed
Monday through Friday
CPT Code Information
0027U-JAK2 (Janus kinase 2) (eg, myeloproliferative disorder), exon 12 sequence and exon 13 sequence, if performed
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| JAKXB | JAK2 Exon 12 Mutation Detection, B | 55300-8 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 39467 | JAK2 Sequencing Result | 55300-8 |
| 20194 | Final Diagnosis: | 34574-4 |
Interpretation
The results will be reported as 1 of 2 states:
1. Negative for JAK2 mutation
2. Positive for JAK2 mutation
If the result is positive, a description of the mutation at the nucleotide level and the altered protein sequence is reported.
Positive mutation status is highly suggestive of a myeloproliferative neoplasm but must be correlated with clinical and other laboratory features for a definitive diagnosis. Negative mutation status does not exclude the presence of a myeloproliferative or other neoplasm.
Report Available
5 to 8 daysMethod Name
Sanger Sequencing
Forms
1. Hematopathology Patient Information (T676)
2. If not ordering electronically, complete, print, and send a Hematopathology/Cytogenetics Test Request (T726) with the specimen.