Use of test
Mutations in the thrombopoietin receptor (MPL gene) have been described in 3-5% of patients with essential thrombocythaemia (ET) and primary myelofibrosis (PMF). The two most common MPL mutations are targeted in this test: W515K and W515L.
MPL mutations are not typically seen in patients with polycythaemia vera.
MPL mutation testing helps to differentiate ET/PMF from a reactive process. The presence of a MPL mutation provides strong evidence for ET or PMF; the absence of a MPL mutation does not exclude a diagnosis of ET or PMF.
This is an assay for non-heritable mutations. It does not raise issues of ethics or consent that are different from most other investigations ordered in the routine care of a patient.
Analysis of the sequence of the MPL gene for the presence of W515K or W515L.
Requesting the test
This test is usually requested by a haematologist or oncologist.
1.0 mL of bone marrow in dedicated EDTA or 4 mL peripheral blood in dedicated EDTA
To help ensure the quality of the test, a genetic test should be done with a dedicated sample whenever possible i.e. a sample collected specifically for that test rather than a sample that is used for multiple tests.
We recommend that the patient or another adult check the labelling of request forms and sample containers.
7-10 business days.
This test has a Medicare rebate which, subject to the requirements of the Medicare descriptor being met, may cover all or part of the cost.
The Medicare details, including descriptor and schedule fee, are listed under MBS item 73325.