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Epic Test Code LAB3112 JAK2 V617F Mutation Detection, Blood

Additional Codes

MML Code: JAK2B

LIS Code: JAK2B

NY State Approved

Yes

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Reporting Name

JAK2 V617F Mutation Detection, B

Method Name

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

Specimen Stability Information

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


Shipping Instructions


Specimen must arrive within 7 days of draw.



Specimen Required


Container/Tube:

Preferred: Lavender top (EDTA)

Acceptable: Yellow top (ACD)

Specimen Volume: 4 mL

Collection Instructions:

1. Invert several times to mix blood.

2. Send specimen in original tube.


Specimen Type

Whole Blood EDTA

Specimen Minimum Volume

1 mL

Reference Values

An interpretive report will be provided.

Analytic Time

2 days

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

Reject Due To

Hemolysis

Mild OK; Gross reject

Lipemia

NA

Icterus

NA

Other

Moderately to severely clotted

Testing Algorithm

The following algorithms are available in Special Instructions:

-Erythrocytosis Evaluation Testing Algorithm

-Myeloproliferative Neoplasm: A Diagnostic Approach to Peripheral Blood Evaluation

Cautions

A positive result is not specific for a particular subtype of myeloproliferative neoplasm and clinicopathologic correlation is necessary in all cases. If this test is ordered in the setting of erythrocytosis and suspicion of polycythemia vera, interpretation requires correlation with a concurrent or recent prior bone marrow evaluation.

 

A negative result does not exclude the presence of a myeloproliferative neoplasm or other neoplastic process.

 

In rare cases, a variant other than the V617F may be present in an area that interferes with primer or probe binding and cause a false-negative result.

Supportive Data

Analytical sensitivity is determined at 0.06% (by dilution of a JAK2 V617F-positive cell line into a negative cell line DNA).

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 variant in JAK2 characterized as c.G1849T; p. Val617Phe (V617F). This variant is identified overall in approximately two-thirds of all MPN,(1-3) but the prevalence varies by MPN subtype. The JAK2 V617F variant is present in 95% to 98% of polycythemia vera patients, 50% to 60% of primary myelofibrosis patients, and 50% to 60% of essential thrombocythemia patients. It has also been described infrequently in other myeloid neoplasms, including chronic myelomonocytic leukemia and myelodysplastic syndrome.(4) This variant is not seen in chronic myelogenous leukemia (CML) or in reactive conditions with elevated blood counts. Detection of the JAK2 V617F variant 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 variant (20%-30% of PMF and ET) and MPL exon 10 variant (5%-10% of PMF and 3%-5% of ET).(5-9) Variants in JAK2, CALR, and MPL are essentially mutually exclusive.

Specimen Retention Time

DNA: 3 months

Interpretation

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

-Negative for JAK2 V617F variant

-Positive for JAK2 V617F variant

 

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

 

Negative variant 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.

Useful For

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

Forms

1. Hematopathology Patient Information (T676) in Special Instructions

2. If not ordering electronically, complete, print, and send a Hematopathology/Cytogenetics Test Request (T726) with the specimen.