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.