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JAK2 (9p24.1)
- FISH
Clinical Significance
JAK2 (9p24.1) break-apart test by FISH is useful for detecting JAK2 rearrangements in eosinophilia workup. Eosinophilia is a common feature of the diseases that are recognized by the World Health Organization (WHO) category, Myeloid/lymphoid neoplasms with eosinophilia and rearrangement of PDGFRA, PDGFRB, or FGFR1, or with PCM1-JAK2.
For analysis of JAK2 mutations for suspected myeloproliferative neoplasms (MPN), consider JAK2 V617F Mutation Analysis with or without reflex to JAK2 Exon 12-14 Mutation Analysis by molecular.
Specimen Requirements
Bone Marrow Aspirate: 1-2 mL in sodium heparin tube. EDTA tube is acceptable.
Peripheral Blood: 2-5 mL in sodium heparin tube. EDTA tube is acceptable.
Fresh, Unfixed Tissue: Tissue in RPMI.
Bone Marrow/Peripheral Blood Smear or Fresh Tissue Touch Preparation Slides: Minimum 1 slides, labeled with specimen type.
Fluids: Mix in equal parts with RPMI (specimen volume to RPMI ratio of 1:1).
Fixed Cell Suspension: A client-prepared fixed cell suspension is acceptable if received in 3:1 Methanol:Glacial Acetic Acid.
Storage and Transportation
Use cold pack for transport, making sure cold pack is not in direct contact with specimen. For fresh samples: refrigerate before shipping and ship same day as drawn whenever possible. Do not freeze. NYS clients please provide date and time of Collection.
CPT Code(s)*
88374x1 automated or 88377x1 if manual analysis is performed.
*The CPT codes provided with our test descriptions are based on AMA guidelines and are for informational purposes only. Correct CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed.
Last Updated: September 17, 2025