<b>Peripheral Blood:</b> 3-5 mL in EDTA tube. Sodium Heparin is acceptable.</br>
<b>Note:</b> Test is DNA-based. Please select Extract & Hold - DNA if specimen hold service is desired.</p>
Tests may also be ordered individually.</br></br>
<b>Note:</b> This assay replaces the former MPN JAK2 V617F with Sequential Reflex to JAK2 Exon 12-13, CALR, and MPL performed by PCR/fragment analysis/bi-directional sequencing. NY samples are still processed by PCR/fragment analysis/bi-directional sequencing until further notice.</p>
Identification of myeloproliferative neoplasm (MPN)-associated driver mutations is important in the diagnosis, prognosis and therapy selection of BCR-ABL1-negative MPN. JAK2 V617F represents the canonical exon 14 gain-of-function mutation, which has been reported in >95% of patients with polycythemia vera (PV) and approximately 50-60% of patients with essential thrombocythemia (ET) and primary myelofibrosis (PMF). High JAK2 V617F variant allele fraction (>50%) is more commonly observed in PV and is associated with increased risk of myelofibrotic progression in both PV and ET. Targeted therapy directed at the JAK2 V617F mutation is available. A small subset of PV patients that are JAK2 V617F mutation negative will harbor JAK2 mutations in exon 12, usually small in-frame deletions or insertions. JAK2 exon 12 mutated PV shows similar prognosis to JAK2 V617F mutated cases. Other rare non-V617F mutations can be detected in exons 13, 14 and 15 of the JAK2 gene. Somatic insertions or deletions in exon 9 of CALR gene are detected in 25-35% of patients with ET and PMF. The most common CALR mutations observed include a 52bp deletion (type 1) or 5bp insertion (type 2). PMF patients with mutated CALR have a lower risk of thrombosis and longer overall survival than patients with JAK2 and MPL mutation, however, the association may be limited to those with type 1or type 1-like mutation. Exon 10 MPL mutations, most commonly W515 and S505, are present in approximately 5-10% of patients with PMF and ET. MPL and CALR mutations have been associated with increased risk of MF transformation in ET cases. (References: PMID: 35767897, 35732831, 36347013, 37357958, 27187622, 29274140, 26473532, and 38269572)