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HelpTest Code MPNML MPL Exon 10 Sequencing, Reflex, Varies
Specimen Required
Only orderable as a reflex. For more information see MPNCM / Myeloproliferative Neoplasm, CALR with Reflex to MPL, Varies.
Useful For
Aiding in the distinction between a reactive cytosis and a myeloproliferative neoplasm when JAK2 V617F testing result is negative
Evaluates for variants in MPL in an algorithmic process for MPNCM / Myeloproliferative Neoplasm, CALR with Reflex to MPL, Varies
Method Name
Only orderable as a reflex. For more information see MPNCM / Myeloproliferative Neoplasm, CALR with Reflex to MPL, Varies.
Sanger Sequencing
Reporting Name
MPL Exon 10 Sequencing, ReflexSpecimen Type
VariesSpecimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Varies | Varies | ||
Reject Due To
| Gross hemolysis | Reject |
| Paraffin-embedded bone marrow aspirate clot or biopsy blocks Slides Paraffin shavings Moderately to severely clotted |
Reject |
Clinical Information
The JAK2 V617F variant is present in 95% to 98% of patients with polycythemia vera, 50% to 60% of patients with primary myelofibrosis (PMF), and 50% to 60% of patients with essential thrombocythemia (ET). Detection of the JAK2 V617F is helps establish the diagnosis of a myeloproliferative neoplasm (MPN). However, a negative JAK2 V617F result does not indicate the absence of MPN. Other important molecular markers in BCR::ABL1-negative MPN include CALR exon 9 alterations (20%-30% of PMF and ET) and MPL exon 10 alterations (5%-10% of PMF and 3%-5% of ET). Variants in JAK2, CALR, and MPL are essentially mutually exclusive. A CALR variant is associated with decreased risk of thrombosis in both ET and PMF and confers a favorable clinical outcome in patients with PMF. A triple negative (JAK2 V617F, CALR, and MPL-negative) genotype is considered a high-risk molecular signature in PMF.
Reference Values
Only orderable as a reflex. For more information see MPNCM / Myeloproliferative Neoplasm, CALR with Reflex to MPL, Varies.
An interpretive report will be provided.
Interpretation
The results will be reported as 1 of the 3 following states:
-Positive for CALR variant
-Positive for MPL variant
-Negative for CALR and MPL variants
Positive variant status is highly suggestive of a myeloid neoplasm and clinicopathologic correlation is necessary in all cases.
Negative variant status does not exclude the presence of a myeloproliferative neoplasm or other neoplasms.
Cautions
A positive result is not specific for a particular subtype of myeloproliferative neoplasm and clinicopathologic correlation is necessary in all cases.
A negative result does not exclude the presence of a myeloproliferative neoplasm or other neoplastic process.
Method Description
Genomic DNA is extracted, and Sanger sequencing is used to evaluate for alterations in MPL, exon 10. The sensitivity of this assay is approximately 20%, such that samples containing lower percentages of altered DNA will appear negative.(Unpublished Mayo method)
Day(s) Performed
Monday through Friday
Report Available
7 to 10 daysSpecimen Retention Time
Extracted DNA: 3 monthsPerforming Laboratory
Mayo Clinic Laboratories in Rochester
Test Classification
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.CPT Code Information
81339-MPL (myeloproliferative leukemia virus oncogene, thrombopoietin receptor, TPOR) (eg, myeloproliferative disorder), exon 10 sequence