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Test Code JAK2B JAK2 V617F Mutation Detection, Blood

Reporting Name

JAK2 V617F Mutation Detection, B

Useful For

Aiding in the distinction between a reactive blood cytosis and a chronic myeloproliferative disorder in blood specimens

Performing Laboratory

Mayo Medical Laboratories in Rochester

Specimen Type

Whole Blood EDTA


Shipping Instructions


Specimen must arrive within 7 days (168 hours) of draw.



Specimen Required


Container/Tube:

Preferred: EDTA (lavender top)

Acceptable: ACD (yellow top)

Specimen Volume: 4 mL

Collection Instructions:

1. Invert several times to mix blood.

2. Send specimen in original tube.


Specimen Minimum Volume

1 mL

Specimen Stability Information

Specimen Type Temperature Time
Whole Blood EDTA Ambient (preferred) 7 days
  Refrigerated  7 days

Reference Values

An interpretive report will be provided.

Day(s) and Time(s) Performed

Monday through Friday; 12 p.m.

CPT Code Information

81270-JAK2 (Janus kinase 2) (eg, myeloproliferative disorder) gene analysis, p.Val617Phe (V617F) variant

LOINC Code Information

Test ID Test Order Name Order LOINC Value
JAK2B JAK2 V617F Mutation Detection, B In Process

 

Result ID Test Result Name Result LOINC Value
39722 JAK2 Result 53761-3
29590 JAK2 V617F Mutation Detection, B 43399-5

Testing Algorithm

The following algorithms are available in Special Instructions:

-Erythrocytosis Evaluation Testing Algorithm

-Myeloproliferative Neoplasm: A Diagnostic Approach to Peripheral Blood Evaluation

Clinical Information

The Janus kinase 2 gene (JAK2) codes for a tyrosine kinase (JAK2) that is associated with the cytoplasmic portion of a variety of transmembrane cytokine and growth factor receptors important for signal transduction in hematopoietic cells. Signaling via JAK2 activation causes phosphorylation of downstream signal transducers and activators of transcription (STAT) proteins (eg, STAT5) ultimately leading to cell growth and differentiation. BCR-ABL1-negative myeloproliferative neoplasms (MPN) frequently harbor an acquired single nucleotide mutation in JAK2 characterized as c.G1849T; p. Val617Phe (V617F). This mutation is identified overall in approximately two-thirds of all MPN,(1-3) but the prevalence varies by MPN subtype. The JAK2 V617F is present in 95% to 98% of polycythemia vera, 50% to 60% of primary myelofibrosis, and 50% to 60% of essential thrombocythemia. It has also been described infrequently in other myeloid neoplasms, including chronic myelomonocytic leukemia and myelodysplastic syndrome.(4) This mutation is not seen in chronic myelogenous leukemia (CML) or in reactive conditions with elevated blood counts. Detection of the JAK2 V617F is useful to help establish the diagnosis of MPN. However, a negative JAK2 V617F result does not indicate absence of a MPN. Other important molecular markers in BCR-ABL1-negative MPN include CALR exon 9 mutation (20%-30% of PMF and ET) and MPL exon 10 mutation (5%-10% of PMF and 3%-5% of ET).(5-9) Mutations in JAK2, CALR, and MPL are essentially mutually exclusive.

Interpretation

The results will be reported as 1 of the 2 states:

-Negative for JAK2 V617F mutation

-Positive for JAK2 V617F mutation

 

Positive mutation status is highly suggestive of a myeloid neoplasm, but must be correlated with clinical and other laboratory features for definitive diagnosis.

 

Negative mutation status does not exclude the presence of a myeloproliferative neoplasm or other neoplasm.

 

Results below the laboratory cutoff for positivity are of unclear clinical significance at this time.

Clinical Reference

1. Baxter EJ, Scott LM, Campbell PJ, et al: Acquired mutation of the tyrosine kinase JAK2 in human myeloproliferative disorders. Lancet 2005 March 16;365(9464):1054-1061

2. James C, Ugo V, Le Couedic JP, et al: A unique clonal JAK2 mutation leading to constitutive signaling causes polycythaemia vera. Nature 2005 April 28;434(7037):1144-1148

3. Kralovics R, Passamonti F, Buser AS, et al: A gain-of-function mutation of JAK2 in myeloproliferative disorders. N Engl J Med 2005;352:1779-1790

4. Steensma DP, Dewald GW, Lasho TL, et al: The JAK2 V617F activating tyrosine kinase mutation is an infrequent event in both "atypical" myeloproliferative disorders and the myelodysplastic syndrome. Blood 2005;106:1207-1209

Analytic Time

2 days

Reject Due To

Hemolysis

Mild OK; Gross reject

Lipemia

NA

Icterus

NA

Other

Moderately to severely clotted

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.

Method Name

Point Mutation Detection in DNA Using Quantitative Polymerase Chain Reaction (PCR)

Forms

1. Hematopathology Patient Information (T676) in Special Instructions

2. If not ordering electronically, complete, print, and send a Hematopathology/Cytogenetics Test Request Form (T726) with the specimen (http://www.mayomedicallaboratories.com/it-mmfiles/hematopathology-request-form.pdf).