Gene Symbol: JAK2
Chromosomal Locus: 9p24.1
Protein: Tyrosine-protein kinase JAK2
Pseudonyms: Janus kinase 2
TURNAROUND TIME: 8 days
2012 AMA Code: 81270
TESTING METHODOLOGY: V617F Mutation specific polymerase chain reaction (PCR) and fluorescent capillary electrophoresis
- Collect: Prefer one 3ml bone marrow or 3ml whole blood EDTA (lavender top) tube.
- Min. Collection: 0.7 ml bone marrow or whole blood.
- Transport: Room Temp shipped regular next day air (No Saturday delivery; store specimen at 4°C and ship Monday).
- Stability: Ambient: up to 7 days; Refrigerated: 2 weeks. Frozen: unacceptable
- Unacceptable Conditions: Serum. Frozen or severely hemolyzed blood. Clotted blood.
Counseling and informed consent are recommended for genetic testing. A consent form
is available as a resource but not required.
Inheritance: Somatically acquired.
Disease Characteristics: The V617F mutation in the JAK2 gene is commonly found in acquired clonal myeloproliferative disorders. The detection of the mutation confirms the presence of a myeloproliferative disorder that has significant proliferative and survival advantages. Patients with the V617F mutation have a significantly longer duration of the disease with a higher rate of complications (fibrosis, hemorrhage and thrombosis).
Molecular Genetic Mechanism: The Val617Phe (V617F) mutation is in exon 14 at c.1849G>T. The mutation can be present as either a heterozygote or homozygote change.
Clinical Sensitivity: The V617F mutation is found in approximately 90% of Polycythemia Vera (PV), 50% of Essential Thrombocytopenia (ET), and 50% of Primary Myelofibrosis (PMF).
Analytical Sensitivity: 99%
Test Limitations: This test only detects the V617F mutation in exon 14 of the JAK2 gene. This test will not detect exon 12 mutations. Rare diagnostic errors can occur due to primer / probe site mutations or rare polymorphisms.
INDICATIONS FOR USE:
- To identify the non-chronic myelogenous leukemia subgroup of myeloproliferative disorders.
- Presence of JAK2 V617F mutation correlates with risk of thrombosis, marrow fibrosis and patient survival.
- Identify patients who may respond to Jak2 tyrosine kinase inhibitors