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Test ID JAK2P JAK2 (9p24.1) Rearrangement, Hematologic Disorders, FISH, Tissue

Shipping Instructions

Advise Express Mail or equivalent if not on courier service.

Necessary Information

Provide a reason for testing and pathology report with each specimen. The laboratory will not reject testing if this information is not provided, but appropriate testing and interpretation may be compromised or delayed.

Specimen Required

Submit only 1 of the following specimens:


Specimen Type: Tissue

Preferred: Tissue block

Collection Instructions: Submit a formalin-fixed, paraffin-embedded (FFPE) tumor tissue block. Blocks prepared with alternative fixation methods may be acceptable; provide fixation method used.


Acceptable: Slides

Collection Instructions: Four consecutive, unstained, 5 micron-thick sections placed on positively charged slides, and 1 hematoxylin and eosin-stained slide.

Useful For

Providing diagnostic information for hematologic malignancies


Aiding in the determination of whether a targeted JAK2 inhibitor could be useful for therapy

Reflex Tests

Test ID Reporting Name Available Separately Always Performed
_PBCT Probe, +2 No No
_PADD Probe, +1 No No
_PB02 Probe, +2 No No
_PB03 Probe, +3 No No
_IL25 Interphases, <25 No No
_I099 Interphases, 25-99 No No
_I300 Interphases, >=100 No No

Testing Algorithm

This test does not include a pathology consult. If a pathology consultation is requested, PATHC / Pathology Consultation should be ordered and the appropriate fluorescence in situ hybridization (FISH) test will be ordered and performed at an additional charge.


This test includes a charge for application of the first probe set (2 FISH probes) and professional interpretation of results. Additional charges will be incurred for all reflex probes performed. Analysis charges will be incurred based on the number of cells analyzed per probe set. If no cells are available for analysis, no analysis charges will be incurred.


For information see Anaplastic Large Cell Lymphoma Evaluation Algorithm.

Method Name

Fluorescence In Situ Hybridization (FISH)

Reporting Name

JAK2 (9p24.1) Rearrangement,FISH,Ts

Specimen Type


Specimen Minimum Volume

Two consecutive, unstained, 5- micron- thick sections placed on positively charged slides, and 1 hematoxylin and eosin-stained slide.

Specimen Stability Information

Specimen Type Temperature Time Special Container
Tissue Ambient (preferred)

Reject Due To

No specimen should be rejected.

Clinical Information

The JAK2 gene codes for a protein tyrosine kinase involved in cytokine signaling. Chromosomal translocations involving JAK2 can lead to the formation of chimeric oncoproteins in hematologic malignancies. Rearrangements involving 9p24.1 are rare abnormalities seen in various hematologic diseases and are typically aggressive. Identification of opportunities to apply targeted therapy with JAK2 inhibitors can be helpful for patients with JAK2 rearrangements.

Reference Values

An interpretive report will be provided.


A positive result is detected when the percent of cells with an abnormality exceeds the normal cutoff for the probe set.


A positive result suggests rearrangement of the JAK2 locus. A negative result suggests no rearrangement of the JAK2 gene region at 9p24.1.


This test is not approved by the US Food and Drug Administration, and it is best used as an adjunct to existing clinical and pathologic information.


Fixatives other than formalin (eg, Prefer, Bouin) may not be successful for fluorescence in situ hybridization (FISH) assays, however nonformalin-fixed samples will not be rejected. 


Paraffin-embedded tissues that have been decalcified are generally unsuccessful for FISH analysis. The pathologist reviewing the hematoxylin and eosin-stained slide may find it necessary to cancel testing.

Supportive Data

Fluorescence in situ hybridization (FISH) analysis was performed on 2 paraffin-embedded tissue samples from patients with previously identified 9p24.1 abnormality and 25 noncancerous lymph node control specimens. Rearrangement of JAK2 was identified in 2 samples. The normal controls were used to generate a normal cutoff for this assay.

Clinical Reference

1. Chase A, Bryant C, Score J, et al: Ruxolitinib as potential targeted therapy for patients with JAK2 rearrangements. Haematologica. 2013;98(3):404-408

2. Van Roosbroeck K, Cox L, Tousseyn T, et al: JAK2 rearrangements, including the novel SEC31A-JAK2 fusion, are recurrent in classical Hodgkin lymphoma. Blood. 2011;117(15):4056-4064

3. Roberts K, Li Y, Payne-Turner D, et al: Targetable kinase-activating lesions in Ph-like acute lymphoblastic leukemia. N Engl J Med. 2014;371:1005-101

4. Springuel L, Renauld JC, Knoops L: JAK kinase targeting in hematologic malignancies: a sinuous pathway from identification of genetic alteration towards clinical indications. Haematologica. 2015;100:1240-1253

5. Reshmi SC, Harvey RC, Roberts KG, et al: Targetable kinase gene fusions in high-risk B-ALL: A study from the Children's Oncology Group. Blood. 2017;129:3352-3361

Method Description

The test is performed using a laboratory-developed JAK2 (9p24.1) dual-color break-apart strategy probe (BAP). The probe set is hybridized to the appropriate target areas and 2 technologists each analyze 50 interphase nuclei (100 total) with the results expressed as the percent of abnormal nuclei.(Unpublished Mayo method)

Day(s) Performed

Monday through Friday

Report Available

7 to 10 days

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 US Food and Drug Administration.

CPT Code Information

88271 x 2, 88291-DNA probe, each (first probe set), Interpretation and report

88271 x 2-DNA probe, each; each additional probe set (if appropriate)

88271 x 1-DNA probe, each; coverage for sets containing 3 probes (if appropriate)

88271 x 2-DNA probe, each; coverage for sets containing 4 probes (if appropriate)

88271 x 3-DNA probe, each; coverage for sets containing 5 probes (if appropriate)

88274-w/modifier 52-Interphase in situ hybridization, <25 cells, each probe set (if appropriate)

88274-Interphase in situ hybridization, 25 to 99 cells, each probe set (if appropriate)

88275-Interphase in situ hybridization, 100 to 300 cells, each probe set (if appropriate)

LOINC Code Information

Test ID Test Order Name Order LOINC Value
JAK2P JAK2 (9p24.1) Rearrangement,FISH,Ts In Process


Result ID Test Result Name Result LOINC Value
606822 Result Summary 62357-9
606823 Interpretation 69965-2
606824 Result 62356-1
GC052 Reason for Referral 42349-1
606825 Specimen 31208-2
606826 Source 31208-2
606827 Tissue ID 80398-1
606828 Method 85069-3
606829 Additional Information 48767-8
606830 Disclaimer 62364-5
606831 Released By 18771-6