Test Catalog

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

Useful For Suggests clinical disorders or settings where the test may be helpful

Providing diagnostic information and helping to determine whether a targeted JAK2 inhibitor could be useful for therapy

Testing Algorithm Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

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.

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

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 Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

An interpretive report will be provided.

Interpretation Provides information to assist in interpretation of the test results

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.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

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.

Clinical Reference Recommendations for in-depth reading of a clinical nature

1. Chase A, Bryant C, Score J, et al: Ruxolitinib as potential targeted therapy for patients with JAK2 rearrangements. Haematol 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