Diagnosis or differential diagnosis of myeloproliferative disorders by MPL gene analysis using bone marrow specimens
Sanger Sequencing
MPL S505
MPL W515
Myeloproliferative leukemia virus oncogene
MPL
PMF
MPN
ET
Primary Myelofibrosis
Essential Thrombocythemia
Bone Marrow
Specimen must arrive within 7 days of collection.
The following information is required:
1. Pertinent clinical history
2. Clinical or morphologic suspicion
3. Date of collection
4. Specimen source
Container/Tube:
Preferred: Lavender top (EDTA)
Acceptable: Yellow top (ACD solution B)
Specimen Volume: 2 mL
Collection Instructions:
1. Invert several times to mix bone marrow.
2. Send specimen in original tube. Do not aliquot.
3. Label specimen as bone marrow.
1 mL
Gross hemolysis | Reject |
Moderately to severely clotted | Reject |
Specimen Type | Temperature | Time | Special Container |
---|---|---|---|
Bone Marrow | Ambient (preferred) | 7 days | |
Refrigerated | 7 days |
Diagnosis or differential diagnosis of myeloproliferative disorders by MPL gene analysis using bone marrow specimens
Mutations in the JAK2, CALR and MPL genes are considered driver events in the BCR-ABL1 negative myeloproliferative neoplasms (MPN) including polycythemia vera (PV), primary myelofibrosis (PMF) and essential thrombocythemia (ET). The JAK2 V617F mutation occurs in 95% to 98% of patients with PV, 50% to 60% of patients with PMF and 50% to 60% of patients with ET respectively at diagnosis. Other JAK2 mutations in exon 12-15 occur in the remaining patients with PV. Mutations in the CALR gene occur in 20% to 30% of patients with PMF and 20% to 30% of patients with ET at diagnosis. A 52 base pairs deletion (53%) and a 5 bp deletion (32%) are the most common mutations in the CALR gene while other types of mutations may occur in the remaining cases. MPL exon 10 mutations occur in 5% to 10% of patients with PMF and 5% to 10% of patients with ET. Mutations in JAK2, CALR and MPL are mutually exclusive. The JAK2 V617F mutation is detected by quantitative polymerase chain reaction (PCR). The CALR mutations are detected by PCR targeting exon 9. The MPL mutations in exon 10 are detected by Sanger sequencing. All mutations in JAK2, CALR and MPL can also be detected by next generation of sequencing (NGS). In addition to the mutations in JAK2, CALR and MPL, mutations in many other genes including ASXL1, TET2, DNMT3A, SRSF2, SF3B1, U2AF1, ZRSR2, EZH2, IDH1, IDH2, CBL, KRAS, NRAS, STAG2, and TP53 can occur in MPN. These additional mutations are more frequent in PMF and advanced disease, as compared to PV and ET. It is known that mutations in the ASXL1, SRSF2, U2AF1, EZH2, IDH1 and IDH2 are correlated with a poor prognostic risk. While a single gene test on JAK2, CALR and MPL can be clinically useful, all above mentioned gene mutations can be detected by NGS.
An interpretive report will be provided.
The results will be reported as 1 of 2 states:
-Negative for myeloproliferative leukemia virus oncogene (MPL) exon 10 mutation
-Positive for MPL exon 10 mutation
If the result is positive, a description of the mutation at the nucleotide level and the altered protein sequence is reported.
Positive mutation status is highly suggestive of a myeloproliferative neoplasm but must be correlated with clinical and other laboratory features for a definitive diagnosis. Negative mutation status does not exclude the presence of a myeloproliferative or other neoplasm.
A positive result is not specific for a particular diagnosis, and clinicopathologic correlation is necessary in all cases.
A negative result does not exclude the presence of a myeloproliferative or other neoplasm.
Analytical sensitivity is approximately 20% meaning there must be about 20% of the altered DNA in the specimen for reliable detection.
1. Klampfl T, Gisslinger H, Harutyunyan AS, et al. Somatic mutation of calreticulin in myeloproliferative neoplasms. N Engl J Med. 2013;369(25):2379-2390
2. Rumi E, Pietra D, Ferretti V, et al. JAK2 or CALR mutation status defines subtypes of essential thrombocythemia with substantially different clinical course and outcomes. Blood. 2014;123(10):1544-1551
3. Greenfield G, McMullin MF, Mils K. Molecular pathogenesis of the myeloproliferative neoplasms. J Hematol Oncol. 2021;14(1):103
4. Khoury JD, Solary E, Abla O, et al. The 5th edition of the World Health Organization classification of haematolymphoid tumors: myeloid and histiocytic/dendritic neoplasms. Leukemia 2022; 36:1703-1719.
Genomic DNA is extracted from bone marrow, and the MPL exon 10 amplified using standard polymerase chain reaction. The entire exon 10 sequence is obtained using Sanger sequencing (BigDye terminator V3.1 cycle sequencing kid from Applied Bioscience) with analysis on an automated genetic analyzer.(Unpublished Mayo method)
Monday through Friday
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.
81339
Test Id | Test Order Name | Order LOINC Value |
---|---|---|
MPLFM | MPL Exon 10 Mutation, BM | 75033-1 |
Result Id | Test Result Name |
Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
|
---|---|---|
618662 | Final Diagnosis | 69047-9 |
618663 | Method | 85069-3 |
618664 | Signing Pathologist | 18771-6 |
618666 | Additional Information | 48767-8 |
618667 | Disclaimer | 62364-5 |