JAK2 exon 12
Myeloproliferative Neoplasm (MPN)
Both DNA and RNA are extracted. The algorithm starts with a highly sensitive DNA-based JAK2 V617F test by allele specific polymerase chain reaction. If the JAK2 V617F result is negative or very low positive (0.06%-0.6%), JAK2 exon 12-15 Sanger sequencing test will be performed on the stored RNA sample. If a JAK2 V617F mutation (>0.6%) is detected, the algorithm stops and no further testing will be performed.
The Sanger sequencing covers JAK2 exons 12 through the first 90% of exon 15, which spans the region containing essentially all mutations reported in myeloproliferative neoplasms. The following algorithms are available in Special Instructions.
Aiding in the distinction between the myeloproliferative neoplasm polycythemia vera (PV) and other secondary erythrocytosis
1. Invert several times to mix blood.
2. Send whole blood specimen in original tube. Do not aliquot.
3. Label specimen as blood.
2. Send bone marrow specimen in original tube. Do not aliquot.
3. Label specimen as bone marrow.
Specimen must arrive within 5 days (120 hours) of collection.
The following information is required:
1. Pertinent clinical history
2. Clinical or morphologic suspicion
3. Date of collection
4. Specimen source
A positive result is not specific for a particular diagnosis. Correlation with clinicopathologic findings and other laboratory results is necessary in all cases.
If this test is ordered in the setting of erythrocytosis and suspicion of polycythemia vera, interpretation requires correlation with a concurrent or recent prior bone marrow evaluation.
The results will be reported as 1 of the 3 following states:
-Positive for JAK2 V617F mutation
-Positive for JAK2 mutation (other than V617F)
-Negative for JAK2 mutations
If the result is positive, a description of the mutation at the nucleotide level and the altered protein sequence are reported.
A positive mutation status is highly suggestive of a myeloid neoplasm and may support a diagnosis of polycythemia vera in the appropriate clinical setting. Correlation with clinicopathologic findings and other laboratory results is necessary in all cases.
A negative mutation status makes a diagnosis of polycythemia vera highly unlikely, although it does not completely exclude this possibility, other myeloproliferative neoplasms or other neoplasms.