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Test Code JAK2F JAK2 (9p24.1) Rearrangement for Hematologic Disorders, FISH

Necessary Information

Provide a reason for referral 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: Blood

Container/Tube: Green top (sodium heparin)

Specimen Volume: 4 mL

Collection Instructions:

1. Invert several times to mix blood.

2. Other anticoagulants are not recommended and are harmful to the viability of the cells.


Specimen Type: Bone marrow

Container/Tube: Green top (sodium heparin)

Specimen Volume: 1-2 mL

Collection Instructions:

1. Invert several times to mix bone marrow.

2. Other anticoagulants are not recommended and are harmful to the viability of the cells.


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

Useful For

Providing diagnostic information and helping to determine 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 includes a charge for application of the first probe set (2 FISH probes) and professional interpretation of results. Additional charges will be incurred for application of 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.

Method Name

Fluorescence In Situ Hybridization (FISH)

Reporting Name

JAK2 (9p24.1) Rearrangement, FISH

Specimen Type


Specimen Minimum Volume

Blood: 2 mL
Bone Marrow: 1 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Varies Ambient (preferred)

Reject Due To

All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.

Clinical Information

The JAK2 gene is 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 typically aggressive and rare abnormalities seen in various hematologic diseases. JAK2 inhibitors are one of the only therapy options besides a stem cell transplant for 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.

Supportive Data

FISH analysis was performed on 2 bone marrow samples from patients with previously identified 9p24.1 abnormality and 25 noncancerous blood and bone marrow control specimens. Rearrangement of JAK2 was identified in 2 samples. The normal controls were used to generate a normal cutoff for this assay.

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 100 interphase nuclei (200 total) with the results expressed as the percent of abnormal nuclei.(Unpublished Mayo method)

Day(s) and Time(s) Performed

Samples processed Monday through Sunday. Results reported Monday through Friday, 8 a.m.-5 p.m. CT.

Analytic Time

7 days

Specimen Retention Time

Four weeks

Performing Laboratory

Mayo Clinic Laboratories in Rochester

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.

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
JAK2F JAK2 (9p24.1) Rearrangement, FISH In Process


Result ID Test Result Name Result LOINC Value
43674 Result Summary 50397-9
43675 Interpretation 69965-2
43676 Result Table 93356-4
43677 Result 62356-1
CG972 Reason for Referral 42349-1
CG973 Specimen 31208-2
43680 Source 31208-2
43681 Method 49549-9
43682 Additional Information 48767-8
43683 Disclaimer 62364-5
43684 Released By 18771-6